Rainwater Harvesting: an on-farm guide - UK

8/9/2019 Rainwater Harvesting: an on-farm guide - UK

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rainwater asa resource

Rainwater Harvesting:an on-arm guide


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3/44Environment Agency Rainwater Harvesting: an on-arm guide 1

Foreword

Water is essential or arming but

oten is taken or granted.Yet in many

parts o England and Wales water

resources are already scarce and arelikely to become even scarcer as a

result o climate change.

Its the Environment Agencys

job to manage water resources

and to plan to ensure that there

is enough or people and the

environment. We know how

important water is or agriculture

and want to work with armers

to help them make best use

o the water they have. We believe that, although

many armers think careully about using water moreeciently, there is still scope or urther improvement.

Our Water Eciency Awards showcase best practice

and provide cost-eective ideas to reduce water use.

In addition to using water more wisely, rainwater

harvesting is a way o reducing your reliance on mains

water, or on your borehole or spring. Making use o

the rain that alls on your arm buildings can save

you money. It can also mean potentially less storage

or slurry, and reduce the likelihood o contaminated

runo rom yards entering rivers and streams.

Rainwater harvesting might not be suitable or

everyone. But even i it cannot supply all your water

needs its still worth thinking about. It can reduce your

costs and help reduce your environmental impact.

I hope that this booklet will give you some ideas about

what might work on your arm. Do give it a go!

Ian Barker

Head o Water


4/442 Environment Agency Rainwater Harvesting: an on-arm guide

ContentsSection 1 Introduction 3

What is rainwater harvesting? 4

Benets o rainwater harvesting 4

whats in it or you?

What are the wider implications 5

o rainwater harvesting?

Section 2 Things to consider beore installing 8

a rainwater harvesting systemHow much water do I need and 8

what is it used or?

How eciently are you using water? 9

How much rainall do you have? 9

What quality o water do you need? 11

Is it worth harvesting water? 14

What are the costs o running 14

a RWH system?

Do I need any permission to 14install a RWH system?

Section 3 Rainwater harvesting systems 16

Indirectly Pumped Systems 17

Directly Pumped Systems 17

Gravity Fed Systems 17

What system to use? 19

What makes up a RWH system? 19

Filters 19

Ultra Violet (UV) Sterilisation Units 24

Overfow Drainage 27

Pumps 27

Mains Top-up Arrangement 27

Low Cost Systems 27

Section 4 Rainwater harvesting or dierent 34

agricultural sectors

Livestock Sector 34

Pigs and Poultry Sector 35

Arable Farming Sector 35

Protected Cropping Sector 36

Specialist Food Production 36

and Processing

Farm Diversied Enterprises 37

Section 5 Legislation 38

Planning/Building Regulations 38

Water Supply (Water Fitting) 38

Regulations

Environmental Permitting 38

Farmed Animals and Food Production 39

Water Impoundment and Abstraction 39

Nitrate Vulnerable Zones (NVZ) 39

Health and Saety 39

Section 6 Funding support 40

Enhanced Capital Allowance 40

Rural Development Plan or 40

England (RDPE) 2007-2013

Catchment Sensitive Farming 40

Section 7 Contacts 41

Other useul inormation 41

Disclaimer 41



The Environment Agency recognises the need or good

practice advice to help both armers and land managers

establish the most ecient methods o water usage beore

any need to look or new resources.

This booklet provides a guide on appropriate rainwater

harvesting systems available to the agricultural industry.

It describes the material which may well help decide the

construction o the system you want to install tailor-

made to your requirements. Inside, are calculations or

the collection o volumes o water as well as helping to

gauge the size o storage tanks and pumps and ttings

that might be used. Some case studies illustrate water

harvesting systems based on practical experiences

o armers and growers rom the various sectors oagriculture, who have constructed their own schemes.

Throughout the seasons, we all

routinely harvest oten hard-won

rewards in the arming industry but

what o, arguably, the most valuable

crop o all? Rainwater! It is there or

the takingan asset that can save you

money and reap dividends or armingand the environment alike.

Introduction



What is rainwater harvesting?

Rainwater harvesting (RWH) is the collection anduse o rainwater alling onto buildings which would

otherwise have gone down the drains, been lost through

evaporation, or soaked into the ground.

Buildings under construction present the ideal opportunity

to install a RWH system or it can be added to existing

structures. A system may involve diverting drainage to a

tank or reservoir to collect water and i necessary, could

include treatment to improve water quality or specic

uses. Distribution pumps and pipes may also be required

to supply the water to where it is needed on-arm.

There is a RWH system to suit all needs and budgets.

It could simply be created by diverting roo gutters into

a storage tank or water butt, or it could be more complex

involving pumped storage, lters and UV treatment or

use on ready-to-eat crops.

Benets o rainwater harvesting

whats in it or you?Potentially, there are both economic and environmental

benets o rainwater harvesting.

Typicalchargesformainswaterarecurrentlybetween

1 and 2 per cubic metre and are expected to rise in

the uture. Using RWH or some or all water use on-arm

could reduce this expenditure, however savings will

have to be oset against capital and operational outlay

o the RWH equipment.

Wherewaterisdischargedtoasewer,yourwatercompany will charge you a proportion o supply costs

in your water bill or this discharge. Reducing your

mains water use will ensure these additional savings

can be made.

Harvestingandusingrainwatercanreducethequantity

o water entering your slurry store, running across ouled

yards, or entering your dirty water tank. This can mean

a reduction in slurry store size and reduced amounts o

dirty water to dispose o, resulting in cost savings.

Rainwaterdoesnotcontaintreatmentadditives,suchas chlorine, and is thereore considered by some to

be better or irrigation. However, ltration and/or UV

treatment may still be required or some crops.

Rainwaterisalsoconsideredbetterthanmainswater

or spraying some crop protection products.

Introduction

You can reduce the size o the slurry store that you need i you divert cleanroowater away rom the store

By harvesting water not only are you making best use o the water but you canprevent soil erosion and compaction



RWHcanreducedependenceonasupplyfromrivers

and groundwater sources now under increasing

demand rom an increasing population.

RWHcanalsoreducetheriskoflocalisedooding

where water rom large roo areas is not managed

correctly.

Otherbenetsmaybeparticulartoyourfarm,

Haygrove Farm in Hereordshire (Case Study 1) has

ound benets o better soil drainage, improved

humidity levels and plant health.

Some arm assurance schemes actively encourage

the use o RWH.

What are the wider implications

o rainwater harvesting?

Although there are many positive benets rom RWH

systems, there are also wider implications.

RWHcanhaveanimpactonenergyuseandcarbon

emissions where water, weighing 1 tonne per cubic

metre, is pumped to where it is needed around thearm. The change (positive or negative) in energy use

and carbon emissions, resulting rom using a RWH

system, does depend on your current system and

use o pumps.

ThemanufactureandinstallationofRWHsystems

also has an environmental impact.

Inaddition,wherewaterqualityneedstobehigh

or specic uses and water needs to be treated, or

example using ultraviolet (UV) treatment, this can result

in signicantly increased energy consumption on-arm.

Acommonconcernisthatharvestingrainwater

on a large scale may aect the natural recharge o

groundwater and river fows. Whilst this could be an

issue or large systems in very small catchments, in

most cases, even the largest roo areas are still small

compared to the area o a catchment. Furthermore,harvested rainwater is usually used very close to the

point o collection with surplus run-o allowed to soak

away or drained and returned to the catchment.

RWHsystemsareunlikelytoproviderelieftothemains

water supply in times o water shortage, since the low

rainall during droughts is unlikely to be sucient or

rainwater storage. Climate change may exacerbate this

problem in the uture and a RWH system, on its own,

is unlikely to provide enough water or your arm and

so there is likely to be a need or alternative sources.

Introduction

You need to think about how much energy a new system may use



Case Study 1



The site has 120 ha

o tunnels, with 12

ha tted with roo

drains connected

to a natural

reservoir. This

water is pumped

rom the reservoir

to the irrigation

pump house where

it passes through

sand lters, has

ertiliser added

Case Study 1

Haygrove Ltd is a Hereordshire ruit

arm, growing raspberries, strawberries,

cherries, blackberries and blueberries.

The company also market polytunnels,

designed with valley guttering made

o tensioned, clear, polythene sheet

between the ridges and with standardguttering along the sides.

Haygrove Ltd

and then ed back through the tunnels to irrigate

crops grown in containers. An automated irrigation

scheme waters the plants, using individual drippers

running up the rows o plants.

The arm has harvested 5,852 m3 water per year,

and in three years will recoup the additional

investment or replacing old tunnels. Will Delamore,

rom Haygrove, also highlighted other, noticeable

benets, such as better soil drainage between the

tunnels, improved humidity levels inside them and

a marked improvement in plant health through the

use o harvested water.



How much water do I need and what

is it used or?

Beore RWH is considered, all uses o water should beidentied and quantied. The Waterwise on the Farm

booklet (EA, 20071) sets out how to carry out a water audit

on arm and develop an action plan. This methodology is

also detailed in the Eective Use o Water On Dairy Farms

guide(MDC, 20072). To summarise the methodology:

Identifyallsourcesofwateruse.

Calculatecostofwaterusecheckwaterbills,or

look at pumped volumes rom abstracted sources.

You may also want to check changes in water use

through dierent seasons.

Examinehowandwherethewaterisused.

Calculatehowmuchwateryoushouldbeusing.

Waterwise on the Farmis a useul guide.

Identifyandcomparewaterefciencypractices

in order to reduce water use.

Section 2

Things to consider

1 http://publications.environment-agency.gov.uk/pd/GEHO0307BLVH-E-P.pd

2 http://www.dairyco.net/media/10351/eectiveuseowaterondairyarms.pd

3 This is potential as how much you actually collect will depend on the tank size and the number o times that the tank is fushed through overfow.

a rainwater harvesting system

beore installing

Thekeyissuesyou needtoworkout

beforeyoudecide whether aRWH

system isrightforyourfarmare:

Howmuchwaterisused?

Whatisitusedfor?

Howefcientlyisitbeingused?

Isthereenoughrainfall?

Isthereasuitablecollectionarea?

Whatqualityofwaterisneeded?

WhataretheenergyorcarboncostsofimplementingaRWHsystem?

Isitworthharvestingwater?

Thissectionwilltellyouhowto

answerthese questionsbefore

yougoanyfurther.



How eciently are you using water?

Beore installing a RWH system you should identiy

opportunities where water could be used more eciently

on your arm. There is no value in investing in a RWH

system i water is simply wasted. There are a number

o ways to improve the eciency o water use on-arm

at low or minimal cost.

Five things to consider are:

1 Preventing and repairing leaks.

2 Reducing pressure.

3 Fixing dripping taps and hosepipes.

4 Alternative washing and cleaning processes.

5 Correct scheduling o irrigation to meet crop needs

and reduce evaporation.

Further inormation and guidance on using

water eciently on-arm can be ound onwww.environment-agency.gov.uk,

www.envirowise.gov.uk and www.ukia.org

How much rainall do you have?

The amount o rainall available or collection is a key

actor in the success o any RWH system. The amount

o rainwater available or collection depends upon:

Rainfall;

Roofarea;

Run-offcoefcient;

Filterefciency.

The collectable rainall can be calculated by:

Potential3 collectable rainall (litres) = roo area (m2) x

run-o coecient x lter eciency actor x annual rainall

(mm) (see worked example).

Roo Area: The roo area is the surace that will collect

and channel rainwater to the storage tank. A 1000

tonne grain store on a arm would have an area o around

500 m2. The area is calculated by multiplying the widthby the length o the roo, so a roo that is 20 m wide and

30 m long would have an area o 600 m2.

Section 2

Beore considering new sources o water supply identiy where you may haveleaks rst

The amount o rainall that can be collected depends on your roo area



Runo Coecient: This coecient determines how much

water will fow rom the roo surace, and how much is lost.

A coecient value o 0 would mean that no run-o occurswhilst a value o 1 would collect all o the rain alling on

the roo.

Table 1. Common roo coecients

Roo Type Coecient

Pitched roo 0.85

Flat roo, smooth surace 0.55

Flat roo with gravel layer or thin tur 0.45(



What quality o water do you need?

Collected rainwater will contain traces o environmentalpollutants, animal and bird aecal matter and

vegetation, such as leaves and moss. There may also

be a risk o contamination rom the roo and drain

structures to consider, such as asbestos or lead. All this

must be evaluated beore you install any RWH system.

Quality or crop irrigation. I harvested water is used

or crop irrigation, there are recommended standards

set out by the World Health Organisation (WHO). Many

ood assurance schemes and ood retailers will have

additional requirements or irrigation which will haveto be achieved to meet their contract. These are usually

more rigorous than the WHO recommendations.

Quality or animal drinking. Beore using rainwater,

you should check that this does not breach any hygiene

or arm assurance scheme requirements. The Dairy

Hygiene Regulations require that any water used or

hand, udder or dairy plant washing must be rom a

potable source. This normally means that in dairies,

this water will come rom mains water supply. The

National Dairy Farm Assurance Scheme (NDFAS)requires water or animal drinking to be resh and

clean, and so collected rainwater will need to be

ltered to meet those standards and i necessary,

treated. Filtration and treatment should be considered

or all livestock drinking water.

Section 2

4 Envirowise 2008, Reducing mains water use through rainwater harvesting: EN896. www.envirowise.gov.uk

Rainall (mm)

500 - 640 641 - 740 741 - 870 871 - 1060

1061 - 1290 1291 - 1590 1591 - 6000

Table 2. Harvested rainwater quality and possible treatments (adapted rom Envirowise, 20084)

Water Use

Plant nurseries

Field irrigation

Buildings and armyard cleaning

Toilet fushing

Machinery cleaning

Filter backwashing

Cleaning o equipment or

process cleaningSprayer wash out

Quality Required

Water is not used or consumption

and there is a very low risk o contact.

Water should look clean and be

odour ree.

Water is not used or consumption

and there is low risk o contact. Watermust be clean and odour ree but not

necessarily sterile.

Treatment Options

First fush diverted

Coarse lter

Sand lter

All o the above, plus

Fine lter (possibly membrane lter)

Figure 1 Annual average rainall in the UK

(Environment Agency)



Case Study 2



Farm manager Alex Pike, has designed and built

the bespoke system on the arm to collect all therainwater in two lagoons, which is then treated in

a water-cleaning plant to use as drinking water or

the 1.4 million hens on the site.

About 750,000 has been invested on the one arm,

to harvest and treat all the water generated rom

rain on the site. The annual water charge used to be

120,000 per year, but Alex estimates the harvesting

system can meet nearly the ull water demand on the

site, with mains supply used only or sta acilitiesand or supplementing the harvested water in

extreme dry conditions. This was a large investment,

but i the system covers the previous potable

demand and maintenance costs are low, it could

pay or itsel in around 6 years.

Case Study 2

Oaklands Farm Eggs Ltd is a

company in Shropshire. One o

the arm sites has 6.5 ha o total

yard area, including colony egg

production buildings.

Oaklands Farm Eggs Ltd



Disease control is a concern in the intensive pig and

poultry industries, particularly with the risks posed rom

wild birds. Because o this, the level o treatment to run-orequired to provide adequate biosecurity could rule out

the use o RWH as drinking water or intensive pig and

poultry units, but it could be used or cleaning purposes.

At Oaklands Farm Eggs they do use harvested rainwater

or drinking water but only ollowing thorough treatment

which has needed considerable capital investment.

Is it worth harvesting water?

The strongest infuence on the viability o a RWH scheme

will be the economic return. This can be calculated by

working through the questions on water use in Section

2 (above) to determine the present cost o your water

supply, set against the revised costs o using a rainwater

harvesting system as a part supplement. This can be

determined by identiying what type o system you need

(Section 3) and using the costings in Tables 4 and 5.

It is important to considerall the costs, including both

capital and maintenance costs, to determine the dierence

a RWH system can make. You will need to assess your

current energy use or pumping water and compare it to

the planned system.

For example:

A dairy arm with a 200 cow herd, has an annual

water use o 11,300 m3, approximating 7,300 m3

or drinking, 2,190 m3 or milk cooling, and 1,825 m3

or parlour washing.

The arm has a 3,000 m2 roo area, and is in an

area o 700 mm annual rain and could thereorepotentially harvest 1,680 m3 o rainwater.

Some water will overfow the tank and some may be

diverted as rst fush rom the roo. Assuming the

armer can store hal o the 1,680 m3 o rainwater,

including payment or maintenance and pumping,

the potential saving on a water utility bill at 1 per

cubic metre could be approximately 400 using the

harvested water or the parlour washing, or or animal

drinking water. A armer seeking a 10 year pay back

could invest up to 4,000 in water harvesting.

What are the costs o running a

RWH system?All systems will incur operating and running costs, which

you will need to consider beore installing your system.

The costs will relate to the type o system you plan to

install (see Section 3).

A urther running cost is the maintenance o the

system (Table 5). Maintenance should be carried out

in accordance with the manuacturers instructions and

annual testing is suggested or all RWH systems.

Do I need any permission to install

a RWH system?

Although you do not necessarily require permission

to install a RWH system you will need to speak to the

ollowing organisations.

Ifyouareusingharvestedwaterforhand,udderordairy

plant washing or or irrigation o ready-to-eat crops.

This requires you to contact your Local Authority, since

an Environmental Health Ocer will need to assess

the water annually to ensure its purity. You also need

to make sure that it meets the requirements o any

contracts or arm assurance schemes.

Ifyouaredischargingtheoverowwaterfromyour

RWH system into a watercourse. You need to inorm

the Environment Agency as you may require discharge

consent, depending on the quality and quantity o

the water. However, we would much preer any clean

overfow to go directly to soak-away to prevent fooding.

Ifyouaredischargingcleanoverowwaterintosurface

water drains. This is permitted but only providing it is

uncontaminated. I water is contaminated (runs across

dirty yards, collected rom roo vented poultry houses)

it should be collected in the dirty water system or

treatment or disposal. Again, we would much preer

any clean uncontaminated overfow to go directly to

soak-away to prevent fooding.

Section 2



Ifyouaredischarginganycontaminatedwaterintofoul

sewer. You will need to contact your local sewerage

company. In these situations, we would preer you toremove the source o contamination o the overfow

water rather than treat or dispose o the water.

Ifyouaremakingconsiderablealterationstoexisting

buildings or putting up new structures. You will need

to contact your local planning authority to check

whether you planned changes would require planning

permission.

5 Prices are correct in July 2009

6 Leggett, D.J., Brown, R., Brewer, D., Staneld, G. and Holliday, E. (2001) Rainwater and Greywater use in Buildings:

Best practice guidance. CIRIA Report C539, London

Table 3. Typical running costs o a RWH system

Item Electricity usage6 Cost5 Assumptions

Pump 1 3 kW hr per m3 10p 30p m3 10p per kWhr o electricity

UV unit 120- 140 kWhr per year 12 14 per year 10p per kWhr o electricity

and the unit operates

24 hours a day

Table 4. Regular maintenance activities and cost

Component o system Maintenance requency Cost5

Manually cleaned lters Clean monthly None i carried out by system owner

Sel cleaning and/or coarse lters Check and clean every 2-3 months None i carried out by system owner

Roos and gutters Clean once or twice a year depending 50 - 100

on site conditions

Cartridge lters Replace every 3-6 months depending 25 - 60 or 4 lters

on the suspended solid loading o

the source water

UV bulb Replace every 6 months to 1 year 10 - 70 per bulb

Annual maintenance contract Annual site visit by an engineer 250 per year

who will:

checkandcleanlters;

checkpumpandrepair/replace

asrequired;

replaceothercomponents.

Section 2



The ollowing section gives details o three

dierent systems:

indirectlypumped;

directlypumped;

gravityfed.

The other elements o a RWH system

detailed in this section are:

lters;

treatmentsystem;

storage;

overowdrainage.

Use o low cost rainwater harvesting

systems are also introduced.

Section 3

harvesting systems

RainwaterTherearemany differentRWH

systemsbutthey all havethe

following features:

thewaterisrstcollected,ltered

andthenstored;

wateristhenpipedorpumped

directlyto thepointsofuse, orto

aninternal breaktank;

ifthesystemrunslowonrainwater,

amainswater (orother)backup

willguarantee continuoussupply;

whenitrainsagain,thesystem

changesautomaticallybackto

prioritisetheuseofrainwater.



Section 3

Indirectly Pumped Systems (Figure 2)

Rainwater is initially held in a storage tank and then pumped to a header tank. Water is delivered to appliances via gravity.

Advantages

I the pump ails then water is still supplied via the

mains top-up unction.

Low cost pumps.

Simple controls.

Energy ecient as the pump runs at ull fow.

Disadvantages

Water is delivered at low pressure

(may be solved by using a hybrid system).

Requires a header tank which can add to the overall cost.

Need or sucient roo space, or high tank mounting.

Issues with high, structural loads.

Directly Pumped Systems (Figure 3)

A directly pumped system is a pressurised system. Rainwater, collected and held in a storage tank or reservoir,

is then pumped directly to the point o use when required. This is typical o most horticultural irrigation applications

as shown in the Hedon Salads case study. There is usually a mains or abstraction supply option that maintains a

minimum level that is able to meet short term demand.

Advantages

Water is provided at pressure.

No header tank is required.

Disadvantages

I the pump ails then no water can be supplied.

The use o mains top-up controls are more complicated.

Gravity Fed Systems

Rainwater is collected rom the roo, ltered and piped by gravity to a storage (header) tank. Water is delivered to

appliances via gravity. Mains top-up water can also be tted i needed.

Advantages

Does not require a pump.

No electrical supply required.

No risk o pump-associated ailure.

Disadvantages

Low water pressure pumps may be required

to boost the pressure.

Issues with high, structural loads.

Water quality issues, due to fuctuating

temperatures in the stored water.

The relative height o the components

(roo, lter, tank) are critical.



Figure 3 Principles o a direct system

Recycled water

Rainwater

Service pipework

Priniciples o a direct system

Firststagelter/collector

Storagetank

Controlpanel(powerrain)

Controlpanel

Tank Access

Storage tankDirty water to waste

Rainwater inlet 1Rainwater inlet 2

Drainage pipework

First stage lter

Overfow &anti-backfow

Section 3

Figure 2 Principles o an indirect system

Mains water connection

Recycled water

Rainwater

Mains inlet service

Service pipework

First stage lter rainwater inlet Tank Access

Overfow& anti-backfow

Storage tank

Drainage pipework

Header tank

Pump

Priniciples o an indirect system

Firststagelter/collector

Storagetank Highlevelheadertank

Cleaned water to storage

Pump

Mains water connection



What system to use?

For irrigation applications, the direct pumped systemis the most common because they t typical irrigation

system congurations. However, or low fow intermittent

applications, indirect pumped systems are generally most

appropriate because:

peakdemandscanbehigh,withlongperiodsofnoow;

ifthepumpfails,theheadertankactsasafailsafe

becausewatercanstillbesuppliedviagravity;

theheadertankeasesthedemandonthepump,

increasing pump reliability and lie expectancy.

What makes up a RWH system?

A RWH system comprises a number o components.Some o the parts are specic to RWH and some are

part o the building such as guttering and donwpipes.

Filters

It is recommended that rainwater is ltered beore entry

into the storage tank. The lter should be easy to clean

(or sel-cleansing) and should not block easily. I you

require high quality water, then additional ltration

is also required ater the storage tank.

Name Description Suitability Cost7

Crossfow A mesh screen that splits the water Beore storage tank 500 - 2,500

into two parts. The 1st part passes Sel cleaning

through the mesh to the storage tank.

The remaining water is used to clean

the mesh o any debris and goes

straight to the sewer system/soak away

Vortex Form o cross fow lter Roo areas up to 3,000 m2 500 - 2,000

Beore storage tank

Sel cleaning

Cartridge Requires water to be passed through Ater storage tank 160 - 700

them under pressure Not sel cleaning

Pre-ltration is required

Require replacement every3 months

Fine Mesh Placed in-line or at the inlet to Typically 300 micron screens 40

submersible pumps 100 micron screens or

trickle irrigation

Cannot be retro tted

Ater storage tank

Sand Uses the ability o lter sand to sel Horticultural irrigation systems 400

grade so that the lter medium Can be constructed on large sizes

becomes progressively ner, through or large fow rates

the bed Sel cleaning

Ater storage tank

Table 5. Types o lters

7 All costs are current as o July 2009

Section 3



Case Study 3



Hedon Salads are the largest growers

o cucumbers and aubergines in the

UKbut they also grow other crops,

including peppers. General Manager

Phil Clarkson runs 40,000 m2 o

glasshouses at Burstwick Nursery.

Case Study 3

Rainwater is collected rom a proportion o these

houses and channelled to a reservoir next to the

greenhouse complex. The water is used in the

hydroponic plant-eeding system, rom the rst

week in January until the end o October.

The system is gravity-collected rom the roos and

then pumped rom the reservoir, through a lter, with

automatic back fush, then through a sel-cleaning,main lter and into two 40,000 litre stores, which

supply the greenhouse Rockwool-based growing

system. The site benets rom 8,500 m3 o harvested

water which saves 8,500 on the annual water bill.

The 16,000 invested in the reservoir, pumps and

ltration system was repaid in two years.

Hedon Salads



Case Study 4



A resh produce company,

Fresca Group, in Spalding in

Lincolnshire has used harvested

water rom cold store roos or

air humidication in the root

cold stores.

Case Study 4

The water harvesting system was incorporated into

the original building design, constructed in the mid

1990s, connecting the gutters into 150 mm pipes in

the eaves to drain to the 25 m3 above ground water

storage tank. The rainwater supplements the mains

water supply to the tank.

The system has harvested 400 m3 per year rom a

roo area o 750 m2 which is then pumped into thecold stores humidication system. The company

currently pays 1.08 per cubic metre or water,

including a standing charge or supply and so can

save over 430 each year on water charges, i all the

harvested water is used. It is now planned to divert

harvested water or use in the hydroponic irrigation

system o the chicory growing rooms on the site.

Fresca Group



Ultra Violet (UV) Sterilisation Units

I you require water that is ree rom pathogens, such asor ready-to-eat crops, then a sterilisation unit must be

installed. UV radiation is eective at killing a wide range

o waterborne bacteria, pathogens and viruses. This has

a number o advantages:

easeofuse;

requiresnochemicals;

itisquick;

noeffectonthechemicalcharacteristics,

tasteorodourofthewater;

maintenanceisnotonerous;

noriskfromexcessiveuse,asmightbethe

casewithchemicaltreatment;

however,UVsystemsareenergyintensiveto

use and thereore may not be the best solution

or high quality water on your arm.

A complete UV sterilisation unit will have extra lters and

these will need replacing approximately every six months.The UV bulb consumes electricity and will generally need

replacing ater six months o use. The cost o UV units

depend on the fow rate required, but as a guide can be

rom 360 (8 litres per min) up to 710 (54 litres per

min). The energy cost associated in running the UV units

also needs to be taken into consideration. On average, the

Be aware o health and saety when using above ground stores A new large above ground store

UV unit electricity consumption will be 120 140 KWhrper year. Assuming the UV unit operates 24 hours a day

and the average cost o electricity is 10p then the annual

cost o running one UV bulb is 12 14.

Storage

It is important that you have sucient storage to meet

your needs and can accommodate the amount o water

to be harvested. It is also recommended that the tank

should be sized, so that it overfows at least twice a yearto remove foating debris.

Above Ground Storage

There is usually adequate space on-arm or the use o

above ground storage tanks and, the height o modern

agricultural buildings is sucient to enable rainwater

harvesting by gravity. Where tanks are above ground,

tting insulation and rost protection to pipes and pumps

close to the tank, is recommended. Covers or the tank

are also needed to prevent debris, leaves and access

o animals and birds. Covers can be made o the same

material as the tank, or in Robin Bucks case he uses

a large circular above ground storage tank or his

rainwater with a canvas cover.



Figure 4 Examples o above ground storage tanks The advantages and disadvantages o above groundtanks include:

Advantages

Ease o inspection.

Ease o repair and maintenance o the tank

and equipment.

Lighter and less expensive construction.

Easier to add or increase capacity.

Lower cost o installation.

Avoids groundwater problems (high water table).

Disadvantages

Risk o rost damage to the pipe and equipment.

Occupies ground space.

Susceptibility to damage/vandalism.

Appearance.

Requires a cover.

More susceptible to algal growth and poor

water quality.

Requires a tank specically designed or

use above ground.

Reservoirs

Where water is collected over a large area, such as on

polythene tunnels or glasshouses, a clay or synthetic

lined reservoir is oten used. More inormation on what

you need to consider beore constructing a reservoir can

be ound in Thinking o an Irrigation Reservoir booklet.

Reservoirs collecting harvested rainwater can be ideal or irrigation



Section 3

In underground storage tanks ensure you can access the pump or maintenance

Figure 5 Examples o underground storage tanksUnderground storage tanks

Many RWH systems use underground storage tanks.

Installing a tank underground will result in additional

installation costs in excavating the ground and, where

water tables are high, securing the tank however, there

are also a number o advantages. An underground storage

tank is used at Humberstone Gol Course in Leicestershire,

which aimed to keep the stored water out o view.

Advantages

It helps to prevent algal growth by shielding the tank

rom daylight.

Protects the tank rom extreme weather conditions

such as rost damage.

Protected against mechanical damage.

Helps to regulate the water temperature in the tank,

keeping it cool and limiting bacterial growth.

Saves space on site.

Hidden rom view at ground level.

Disadvantages

Additional cost o excavation.

Additional cost o installation, particularly in high

water tables.

Less accessible or inspection and maintenance.

Roowater enters the drinking trough and a level overfow takes it to the suracewater drains

Images: o WPL Ltd



Section 3

Pumps are needed to ensure the right pressure or the use o water

Overfow Drainage

Storage tanks must have a controlled overfowarrangement to:

preventlocalisedoodingifthecapacity

ofthetankisexceeded;

helpavoidstagnationofstoredwater;

removeoatingdebris.

The overfow can be connected to a soak-away,

inltration device, storm drain, or combined sewer

system. An overfow must include an anti-backfow

device (to prevent contaminated water entering the

tanks) and a rodent barrier. Please see Section 2

or permissions needed or managing overfow.

Pumps

Stored water can be pumped either to where the

water is needed, or to a header tank. Pumps can

also be used in gravity ed systems in order to

increase the water pressure. The choice o pump

depends on the application.

Pumps require repair and replacement at

some point, typically ater 5-10 years. It is also

recommended that they are checked on a regular

schedule to ensure they are unctioning correctly.

Figure 6 Low cost systems

Recycled container with lid 6 m3

= 145

Brand New storage tank 2.5 m3

= 465

IBC container (recycled) 1 m3= 70

Mains Top-up Arrangement

Most RWH schemes will have a top up arrangement ortimes o little or no rainall. This is taken rom a water

mains or abstracted supply. I you use a mains top-up

arrangement, then an air gap must be incorporated

that is compliant with the Water Supply (Water Fittings)

Regulations 1991, which makes sure non mains supply

cannot contaminate mains water supply. Pipes carrying

non-potable water should also be clearly identied.

Use o a Water Regulations Advisory Scheme (WRAS)

Water Industry Approved Plumber Scheme (WIAPS)

will ensure that you are compliant.

Low Cost and DIY Systems

In a arm environment, there are many inexpensive RWH

options that could be considered. Recycled containers can be

used or storage, though care must be taken to ensure any

tank is thoroughly clean and does not contain residues rom

previous uses and will not cause any contamination o the

water. Some o the low cost systems can have short payback

times as demonstrated at Brynkinalt arm (Case Study 7).

Disclaimer: Prices are correct at time o print.Images: Smiths o the Forest o Dean Ltd



Case Study 5



Case Study 5

Robin Buck arms 400 ha in the

highly productive area o the

ens in Lincolnshire growing

a range o arable crops and

some specialist crops o Fennel,

Artichoke, Celeriac and Chicory.

The arm has long recognised the value o ecient

resource management installing a rainwater

collection system on an existing machinery store

and later, another system on a new cold store.

The arm harvests 285 m3 per year rom part o an

840 m2 machinery building, collected in a circular

above ground store which is used or the arm crop

sprayer. When a new 900 tonnes capacity cold storewas constructed on the arm last year, Robin was

determined to include water harvesting and now

the roo water is used to supply 5.4 m3 per week -

eeding the misters in the store to maintain humidity

or the chicory. The arm pays 1.10 per cubic metre

or water, including standing charges, so the costs

o RWH installation were paid back within a year.

Jack Buck Farms Ltd



Case Study 6



This is a ormer arm located within

the urban area o Leicester which has

diversied into leisure by turning land

and acilities into a gol complex. The

arm house has been converted into a

club house and the roo water rom the

buildings is collected and stored or usein the gol greens irrigation scheme.

Case Study 6

The buildings have a guttering system which drains

into a brick-built, underground pump chamber

installed in the courtyard o the original arm house.

The tank now has a submersible pump, with a foat

switch, to transer automatically the water to the 22

m3 capacity above groung irrigation storage tank.

The system supplements the mains water supply to

the tank with 160 m3 per year o harvested water. It

was estimated that these costs were within a 1,000

budget, and the saving o 160 per year on water,

estimated at costing 1 per cubic metre, gives just

over a six year pay back.

Humberstone Gol Course



Case Study 7



Brynkinalt is located in Wrexham.

A DIY rainwater storage system

has been installed by the armer,

David Manord.

Case Study 7

The arm consists o 96 ha o land in total and has

70 milking cows, 70 ollowers and 100 ewes. Crops

grown are maize and barley to use as cattle eed.

Rainwater is collected rom the roo o twobuildings (1431 m2). The RWH systems on the

two buildings are gravity ed, with rainwater being

diverted via pipes to two storage tanks. One o the

tanks is constructed rom a ormer cheese vat (3.37

m3), the other is a concrete (1.18 m3) structure.

Each tank has an overfow pipe that diverts

any excess water to the surace water drainage

system. The harvested water is used as drinking

water or the cattle. Total costs or installing the

system has been kept low by utilising existing

inrastructure on site. The cost o new pipe work

was approximately 100 and the concrete tank

cost 200. The volume o harvested water is

approximately 479 m3 per year. 1 cubic metre owater is worth approximately 1.20p thereore

each time the tanks are lled a saving o 5.46

is made. This saves David 574 per year and

consequently the system paid or itsel within

the rst year!

An added benet to this DIY system is that roo

water does not run across ouled yards and add

to the stored dirty water.

Brynkinalt Home Farm



Livestock Sector

During a recent study8, it was ound that dairy arms pay

between 31 and 100 per cow, each year or water

and could meet 20% o their water use with rainwater

harvesting. Livestock arms mainly use water or:

livestockdrinking;

livestockfeedpreparation;

pencleaning;

slurrymanagement;

vehiclewashing.

8 ADAS 2008, Resource and Energy Audits Pilot Scheme. Report or Farming Connect Cumbria

Section 4

Rainwater harvesting canbe

usedby all agricultural sectors,

thisincludes:

livestock;

pigsandpoultry;

arable;

protectedcropping;

foodprocessingandstorage;

farmdiversiedenterprises.

Sowhateveryou farm,therecanbe arainwater harvestingsystem

tosuityour needs.

harvesting by agricultural sector

Rainwater



Harvesting and using rainwater, can reduce the

quantity o water entering your slurry store, running

across ouled yards, or entering your dirty water tank.

This can mean a reduction in the size o your slurry

store and in the quantity o dirty water to dispose o

and thereore is cost eective. It may also help you in

complying with Nitrate Vulnerable Zone Regulations,

where volumes o storage are calculated with the

volume o rainwater entering your slurry tank or

lagoon. RWH may also improve your site drainage!

Pigs and Poultry Sector

Pig and poultry housing can be used or rainwater

harvesting and water can be used on-arm or

wash water and dust suppression, but unless the

water is treated it is unlikely to be suitable or

livestock drinking.

Harvesting rainwater prevents clean water running across ouled yards

Section 4

Harvested rainwater can be used or irrigating eld vegetables and potatoes

Arable Farming Sector

On arable arms, there are oten very large areas o

roong which can oer opportunities o rainwater

harvesting, including:

machinerystoresandworkshops;

generalpurposestoresforfertiliserseeds

andsundries;

grain,potatoandvegetablestores.

Use o harvested water on arable arms can include:

irrigationforrootcropsandeldvegetables;

vegetablewashings;

machinerywashing;

cropsprayingandsprayerwashdown;

yardwashing;

dustsuppression.



Harvested rainwater can be used or direct irrigation in protected cropping sector

The level o ltration that is needed depends on the

application. Crop sprayers require low levels o physical

contaminants. Provided that a suitable level o ltration isincorporated into the system, there will be a reliable and

cheap source o water or spray mixes and wash out.

Protected Cropping Sector

Use o harvested water on horticultural sites can include:

irrigationforplants;

wateradditiontohydroponicsystems;

machinerywashing;

cropspraying;

stafftoilets.

In deciding to use harvested water or protected cropping,

it is important to consider crop product quality and

hygiene. Harvested rainwater is suitable or root zone

watering, such as hydroponics, trickle irrigation systems

and ornamentals. It is not suited to overhead irrigation

systems on edible salads or ruit products.

Glasshouses are an obvious source o rainwater

harvesting, since the glass cover over the crop intercepts

the rainall that would otherwise reach the plants inside.

Section 4

Systems are generally gravity-ed to above-ground,

circular, butyl-lined, galvanised steel storage tanks or to

lined reservoirs. The multi-span greenhouses have watergutters and valley drainage, connected to a collector pipe

located at the gable ends. These can be tted to a water

tank. Filtration is generally needed to avoid pumps and

irrigation equipment becoming blocked.

Polythene tunnels: In addition to water saving, rainwater

harvesting reduces drainage problems around the tunnels

as well as humidity inside them, while outside, soil erosion

is reduced and vehicle movements become easier.

Specialist Food Production

and Processing

Food production and processing is generally a housed

operation, where roos can be used or RWH. There are

strict hygiene regulations or the quality o water to be

used in direct contact with ood, requiring the water to

be treated to drinking standards. Other uses or water

on site can include:

humidication;

yardcleaning;

vehiclecleaning;

stafftoilets.

Harvested rainwater can be used in your sprayer once ltered to ensure thenozzle will not block



Glasshouses give an ideal opportunity or rainwater harvesting Harvested rainwater is collected rom polytunnels in the guttering shown and thencollected in the lined reservoir to be used or irrigation

Rainwater can be used or many purposes around the arm

Even diversifed arm enterprises fnd that rainwater harvesting can help their business

Section 4

Farm Diversied Enterprises

Farms are diversiying into a whole range o otheractivities, with buildings oten converted and then

rented to small enterprises. Harvested water can be

used or servicing these diversied buildings to include:

yardcleaning;

vehiclecleaning;

stafforcustomer;

otheruses,specictodiversication.



Planning/Building Regulations

Sections o The Building Regulations 2000 will aect

positioning o any tank and pipes (Part H: Drainage and

WasteDisposal;andPartG:Hygiene). Both o thesedocuments can infuence the design o the RWH system.

Planning permission may be needed or structures

such as tanks, lagoons, or pump sheds, depending

on size and location so it is advisable to speak to

your local planning authority beore installing a

rainwater harvesting system.

Section 5

LegislationWater Fitting Regulations

Where mains water supply is used on any premises

in the UK, the Water Supply (Water Fittings) Regulations

(1999) (or Byelaws 2000 in Scotland)must be adhered

to. These regulations prevent the misuse, waste, undue

consumption or erroneous measurement o water

and most importantly, prevent contamination odrinking water through cross-connections, backfow

or back siphonage into the mains rom non-mains

sources, including harvested rainwater. In addition,

water supplied that is not or drinking must be clearly

marked. Using a plumber approved by WIAPS9, should

ensure this. More inormation can be obtained rom the

Water Regulation Advisory Scheme (WRAS)10.

Environmental Permitting

I you run a pig or poultry unit with more than 750 sows,

2,000 production pigs over 30kg or 40,000 poultry

(includes chickens, layers, pullets, turkeys, ducks and

guinea owl), the Environmental Permitting (England

and Wales) Regulations 2007state you will need to

have an environmental permit. Permits require that

operators optimise water use, and reduce waste water

production and require the permit holder to review site

drainage. This should be detailed in a review o water

use on-arm which could include RWH as an alternative

source o water supply. More inormation is available onenvironmental permitting rom the Environment Agency.

9 http://www.wras.co.uk/WIAPS/

10 http://www.wras.co.uk/PDF_Files/IGN%209-02-04%20Reclaimed.pd http://www.wras.co.uk/PDF_Files/AGRIPREM.PDF

IfyouarethinkingofinstallingaRWH

system,youneedto be awareofsome

legislationthatmayapply toyou.

Thisincludes:

Planningandbuildingregulations;

Waterttingsregulations;

Environmentalpermitting

forpigs andpoultry;

Farmedanimalsandfoodproduction;

Waterimpoundmentandabstraction;

NitrateVulnerableZones;

HealthandSafety.



Section 5

Farmed Animals and Food Production

The Food Hygiene (England) Regulations 2006and

The Food Hygiene (Wales) Regulations 2006require

that ood business operators do not use any substance,

other than potable water or clean water, to remove

surace contamination rom products o animal origin,

unless use o the substance has been approved. I it is tobe used or such a purpose, harvested water needs to be

assessed annually by the local authoritys Environmental

Health Ocers.

The Welare o Farmed Animals (England) Regulation

2000state that all animals shall either have access to a

suitable water supply and be provided with an adequate

supply o resh drinking water each day or be able to

satisy their fuid intake needs by other means. The

National Dairy Farm Assurance Scheme (NDFAS)requires

water or animal drinking to be resh and clean.

Water Impoundment and Abstraction

The Water Resources Act 1991 and The Water Act 2003

apply to the impoundment (storage) and abstraction o

water. These require anyone who intends to impound or

abstract water (more than 20 cubic metres per day) rom

any inland waters to obtain either an impounding licence

or an abstraction licence rom the Environment Agency.

I you intend to store harvested rainwater in an articialpool which is sel contained and ed only by the rainwater

or natural runo, then no licence is needed. I harvested

rainwater is diverted to a natural pool or pond which is

ed rom, or eeds to, other water sources then a licence

will be required. I in any doubt about the requirement o

a licence, contact the Environment Agency or clarication.

Nitrate Vulnerable Zones (NVZ)

NVZs are designated areas where nitrate pollution

is considered to be a problem. The regulations aect

how to determine minimum manure and slurry

storage requirements and capacity or the closed

spreading periods.

Other liquids rom average rainall and washings thatare collected and mixed with the slurry must be included

in the capacity requirement. I existing storage is not

sucient to cover the closed period, then the armer

will need to consider either extra storage, or methods

to remove excess dilution. RWH o clean roo water and

clean runo is one way in which excess volume o slurry

can be avoided. More inormation is available on NVZs

rom the Environment Agency.

Health and Saety

Storage o water on arm may pose a health risk where

conditions result in contamination o the water. Harvested

rainwater should not be used or drinking. Taps and pipes

containing harvested water should be clearly marked.

There may be a number o risks around storing and using

non potable water including legionnaires disease11 and

weils disease12. In addition, there are hazards o enclosed

spaces, alls and structural ailures associated with

rainwater harvesting. You should consult the Health andSaety Executive or urther inormation about health and

saety considerations when storing water.

11 http://www.hse.gov.uk/pubns/iacl27.pd

12 http://www.hse.gov.uk/pubns/indg84.pd



Section 6

Funding supportEnhanced Capital Allowance

The Enhanced Capital Allowance (ECA) Scheme 1

enables businesses to claim 100% rst year capital

allowances or investment in rainwater harvesting

equipment, named in the Water Technology List.

The ollowing equipment is supported:

monitoringandcontrolequipment;

rainwaterltrationequipment;

rainwaterstoragevessels;

rainwatertreatmentequipment;

waterefciencyequipment.

Contact:

Envirowise Advice Line 0800 58 57 94

or email: [email protected]

http://www.eca-water.gov.uk/

Rural Development Plan or England

(RDPE) 2007- 2013

Funding is available through the Regional Development

Agencies or measures that increase the resource

eciency o rural businesses. Some RDAs may provide

grants or rainwater harvesting, oten when used in

conjunction with a larger scheme on-arm.

Contact:

Dera: http://www.dera.gov.uk/rural/rdpe/index.htm

RDAs: http://www.englandsrdas.com/visit_rdas/

Catchment Sensitive Farming

For arms in catchment sensitive arming priority areas, as

identied within the England Catchment Sensitive Farming

Delivery Initiative (ECSFDI), there may be grants available

or rainwater storage tanks, rst-fush rainwater diverters

and downpipe lters.

These grants do not cover pumps etc. and advancedtreatment or re-use, but would cover tanks and supply

drainage. Check the Dera website to nd out i you are

in one o the 50 catchments across the country and

check what grants may be available.

Contact:

Natural England (0845 600 3078)

www.dera.gov.uk/arm.environment/water/cs/

delivery-initiative.htm

www.magic.gov.uk/staticmaps/national.asp(maps showing priority catchments)



Environment Agency

Phone: 08708 506506

Email: enquiries@environment-

agency.gov.uk

www.environment-agency.gov.uk

UK Rainwater HarvestingAssociation

www.ukrha.org

Agricultural and Horticultural

Development Board

Tel: 0247 669 2051

Email: [email protected]

www.ahdb.org.uk

UK Irrigation Association

Phone: 01427 717627

www.ukia.org/

Envirowise

Phone: 0800 585794

www.envirowise.gov.uk

Met Oce

Phone: 0870 900 0100Email: [email protected]

www.metoce.gov.uk

Water Regulation Advisory Scheme:

Phone: 01495 248454

Email: [email protected]

www.wras.co.uk

Waterwise on the Farm a simple guide to implementing a water

management plan.

Available rom the Environment Agency, LEAF and NFU.

Best Farming Practices Whats in it or you..? Prot rom a good

environment.

Available rom the Environment Agency

Thinking about an Irrigation Reservoir?

Available rom the Environment Agency and the UK Irrigation Association

Effective use of Water on dairy farms.

Available rom Dairy Co (contact via AHDB)

Effective use of Water on dairy farmsDairy Farm DIY Full Audit Pack.

Available rom Dairy Co (contact via AHDB)

EN896 reducing Mains Water Use through Rainwater Harvesting

Available rom Envirowise

BS 8515:2009 Rainwater harvesting systems. Code o practice

Dera and ADAS have produced our best practice guides or irrigators:

Irrigation best practice: Water management or potatoes a guide

or growers.

A guide or container-grown ornamentals.

Water management o soil and substrate-grown crops, a guide

or top and sot ruit growers.

Water management or eld vegetable crops, a guide or vegetable

growers.

Copies are available rom Adas, Boxworth, Telephone +44 (0)1954 268214

Contacts

Section 7

Other useul inormation

Disclaimer: This booklet is or inormation only. I you are considering installing a rainwater harvesting system, then you should seek proessional advice at all

stages o planning and construction.


44/44

Environment irst: This publication is printed on paper made

rom 100 per cent previously used waste. By-products rom

ki th l d d ti d tili

Would you like to ind out more about us,or about your environment?

Then call us on

08708 506 506* (Mon-Fri 8-6)

email

[email protected]

or visit our website

www.environment-agency.gov.uk

incident hotline 0800 80 70 60 (24hrs)loodline 0845 988 1188

* Approximate call costs: 8p plus 6p per minute (standard landline).Please note charges will vary across telephone providers.

Rainwater Harvesting: an on-farm guide - UK

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