Safe distribution of drinking water without disinfectant residual...(Asp. fumigatus, Fus. oxysporum), Stenotrophomonas maltophilia qPCR for detection: • conditions that support/limit

Safe distribution of drinking water

without disinfectant residual

Gertjan Medema

Chief science officer KWR / Chair on Water and Health Delft University of Technology

The Netherlands

16 milion people on

40.844 kms

The road to distribution of drinking water




1970: chlorination in water treatment of surface water supplies (breakpoint chlorination) and in distribution network

1974: Dr. J. Rook of Rotterdam Water Supply discovered THM formation by chlorination in surface water treatment

1975 - 1980’s: research into THM formation, precursor removal and toxicity and significant reduction of chlorine dose used for breakpoint chlorination, transport chlorination, lower doses in summer


without disinfectant residual 2

1980’s: research showed chlorination in distribution

network has significant contribution to THM

formation

1980’s: water utilities significantly reduced chlorine

dose in network. No residual in all the network, only

network close to treatment works.

1980’s: follow-up monitoring of reduced chlorination

in network: less THMs, coliforms and HPC no

increase



1983: Amsterdam Water Supply experimented with stepwise

reduction of post-treatment chlorine dose to zero and monitored

water quality

Even though DBP concentrations below 10-6 lifetime risk, post-

chlorination was stopped, in Amsterdam and other surface water

supplies.

+ HOCl -HOCl

THMs 12-22 ug/l 0 ug/L

Ames response + -

Ecoli/enterococci 0/100 ml 0/100 ml

HPC 2-5/ml 2-5/ml

AOC - 40%

Chlorination in surface water treatment

replaced by other disinfection processes

Amsterdam (Waternet): ozone + slow

sand filtration

Rotterdam (Evides): UV (2005)

South-west Netherlands (Evides): ozone

North-west Netherlands (PWN): UV/H2O2

(2004)

Since 2005 chlorination only used in

emergency contaminations Evides

205 27mve 12

Noblesse oblige!

Maintaining and demonstrating safety

of distributing drinking water without

disinfectant residual

Part 1: barriers against ingress of

microbial contaminants

Barriers against contamination of the

distribution system

Hygiene code - Distance from source

- Construction

- Maintenance/repairs

Structural integrity - Material approval codes

- Construction codes - Backsiphonage protection

Hydraulic integrity - Pressure

- Continuity of supply

- Redundancy

Distribution system

Is better sentinel in

unchlorinated systems

Microbial monitoring

Distribution networks in the Netherlands

Geographic situation

Flat, little seismic activity

Clay, loam, sand, peat soils

120.000 km

50% PVC

30% AC

10% CI

10% other

Very low leakage (<3%)

Water demand 125 L pppd

Leakage rates (VEWIN, 2005, DVGW, 2008)

Are the barriers against ingress

working and effective?

1. Health data

2. Water quality data

3. Utility performance data



1. Health data

Waterborne outbreaks



Outbreaks via community water supplies

USA 1971 – 2002: 671 outbreaks (19% via distribution and increasing)

= 0.08 per million people per year

Europe 1990-2004: 86 outbreaks (33% via distribution):


NL 1981 – 2012: 2 outbreaks (100% via distribution)


No evidence that absence of residual in water would increase risk of

outbreaks



1. Health data

Waterborne outbreaks: no evidence that absence of residual in water

would increase risk of outbreaks


E. coli


Finished water Distribution system

France 369 (54,560) 0.7% 903 (144,138) 0.6%

Netherlands 17 (39,545) 0.04% 99 (107,593) 0.09%

Germany 1 (20,737) 0.005% 15 (12,530) 0.1%

Total 387 (114,842) 0,34% 1,017 (264,261) 0,38%

Country

Samples with positive E. coli detection

Number (total number) %

+HOCl

-HOCl

Statutory E. coli monitoring in tap water

What does it tell us? (Hambsch et al.,2007; van Lieverloo et al, 2006)

France, Germany, Netherlands( 45 million Europeans)

2100 distribution areas

3 years

Repeat samples (NL data): 2.3% E. coli

HOCL certainly not better, but small systems influence picture



1. Health data




E. coli: systems without residual less contamination than with residual




1. Health data





Quantitative Microbial Risk Assessment


QMRA of fecal contamination incidents

(van Lieverloo et al., 2007)

Incident is repeated E. coli detection

1994 – 2003

Netherlands

7 water utilities

50 incidents

5 / year

185000 consumers affected

Probability of being affected by incident:

1.7 x 10-3

Incidents: how long do they last?


Incidents: how contaminated is the water?


Incidents: what is the health risk?


Of incidents we know:

• Duration (reasonably well, mostly not from start)

• Severity ([E. coli]) (reasonably well, mostly not from start)

Severity ([pathogen]) (assumption based on ratio to E. coli)

• # affected consumers (estimate)

In general we know:

• Volume of (cold) tap water that is consumed

• Dose-effect relations pathogens

Calculate probability of infection

Translation to health risk


Probability of infection of incidents >> 10-4

Pathogen data missing



1. Health data





Quantitative Microbial Risk Assessment: incident risk is high




1. Health data

Waterborne outbreaks: no evidence that absence of residual in water would increase risk of outbreaks





Interruption of supply

Water pressure

Operational data distribution networks

(based on Ofwat, 2008)

Main

bursts per

1000 km

Leakage

m3/km/d

Unplanned

interruptions

per 1000

properties

Properties

at risk of

low

pressure

England/Wales 187 10.1 23 0.02%

Scotland 166 21.3 34 0.31%

Canada 66 11.9 21

Australia 4.4 50

Portugal 67 7.0 0.4 (>12 hr)

USA 629*

3

Netherlands 70**

1.6 ***

*LeChevallier et al., 2011 indicate an industry average of 23-27 breaks per 100 miles, or approx. 150 per 1000 km

**All failures, not only main bursts

***Unplanned interruptions in the Netherlands are, on average, 7.5 min per property per year

Pressure logging:

low pressure events, no negative pressure events

00:00 06:00 12:00 18:00 00:00 06:00 12:00 18:00 00:000

1

2

3

4

tijd (26 - 27 aug 2008)

dru

k (

bar

)

NH Hotel

De Ruyterstraat

Burg. Fennemaplein

08:50 08:55 09:00 09:05 09:100

1

2

3

4

tijd (26 aug 2008)

dru

k (

bar

)

NH Hotel

De Ruyterstraat

Burg. Fennemaplein



1. Health data

Waterborne outbreaks: no evidence that absence of residual in water would increase risk of outbreaks





Interruption of supply: low leakage and interruption levels

Water pressure: limited evidence that no negative pressure transients

Part 2: barriers against regrowth of microorganisms

Nutrient limitation = regrowth control

Van der Kooij, van Lieverloo, van der Wielen (KWR)

Barriers against regrowth

R & D: biostability toolbox

Biostable water

- Continuous research & toolbox biostability of water in use since 1980’s

- Industry guideline values for biostable water (AOC, BFP)

Dr. Dick van der Kooij AOC (1980’s) Biofilm monitor

(1990’s)

Boiler

Biofilm monitor

(2000’s)


Biostable water

1 5 10 15 20 25 30 35 40 45 50 Treatment plant

0

25

50

75 Surface water treatment

Groundwater treatment


Biostable water

- Phreatic groundwater & bank filtrate: already very biostable

- Anaerobic, deep groundwater: optimise biostability by

optimising/additional treatment (methane removal, organic

carbon removal)

- Extensive treatment of surface water to remove nutrients

- infiltation in sandy soil

- ozone + biological GAC filtration

- slow sand filtration


Biostable materials

Biostable materials

- Materials testing protocols: low regrowth potential

- Pipes, connections, valves etc.

Biofilm Formation Potential of materials

1,2: Glass; nrs

3,4: Stainless Steel

5-9: hard PVC

10: polypropylene

11-15: high density PE (PE80)

16-20: low density PE (PE40)

21: PE80.

Current R&D

Opportunistic pathogens (molecular methods)

Step 1: priority setting Organism Cases Epidemiology Occurrence Priority

L. pneumophila +++ ++ + Very high

NTM ++ ++ + High

P. aeruginosa + + + High

Pathogenic fungi + ++ + High

S. maltophilia +/- + + Moderate

Acanthamoeba spp. +/- ++ - Moderate

B. cepacia complex +/- + Unknown Low

A. baumannii complex +/- - Unknown Low

Aeromonas spp. +/- - + Low

Y. enterocolitica ++ - Unknown Low

Afipia spp. - - Unknown Low

Bosea spp. - - Unknown Low

B. pseudomallei - ++ Unknown Low

S. negevensis - +/- Unknown Low

E. meningoseptica - +/- Unknown Low

Methylobacteria - - Unknown Low

N. fowleri - +/- Unknown Low

Current R&D

Opportunistic pathogens (molecular methods)

Step 2: development of molecular methods

• Existing: Legionella & host protozoa

• New: non tuberculous mycobacteria, Pseudomonas aeruginosa, pathogenic fungi (Asp. fumigatus, Fus. oxysporum), Stenotrophomonas maltophilia

qPCR for detection:

• conditions that support/limit growth of opportunistic pathogens

Genotyping:

• comparing strains from water & patient

Overview

Providing safe, sustainable and environment-friendly drinking water

- No chlorine residual: research program

- Protection against contamination

- Low leakage rates

- Low levels of interrupted supply, no neg. pressure

- Low levels of outbreaks and contamination incidents

- Protection against regrowth

- Biostable water

- Biostable materials

- Demonstrating due diligence

- Water quality monitoring, microbial risk assessment

- Operational data collection

- BTO research program

Acknowledgements

KWR

Dick van der Kooij, Hein van Lieverloo, Patrick Smeets, Mirjam Blokker, Edwin Kardinaal, Jan Vreeburg, Harm Veenendaal, Anke Brouwer, LMB technicians

Water utilities

Vitens, Brabant Water, Evides, PWN, Dunea, Waternet, WML, Waterbedrijf Groningen, Waterleidingmaatschappij Drente, Oasen.

Waterlaboratories

The Microrisk partners, particularly Beate Hambsch, Emmanuel Soyeux, Jean Francois Loret, Paula Agutter

BTO: Joint Research Program of Netherlands Water Supply, particularly the microbiology program committee

European Commission FP6

Safe distribution of drinking water without disinfectant residual...(Asp. fumigatus, Fus. oxysporum), Stenotrophomonas maltophilia qPCR for detection: • conditions that support/limit

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