Transcript Water Quality Monitoring Through Implementation of Water Safety Plan

Water Quality Monitoring
through implementation of
Water Safety Plan
Dr A Gunasekar
WHO Country Office for India
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Current situation and challenges
•
88% of India’s population is using improved drinking
water sources. (Urban – 96%; Rural – 84%); however
water delivered at the taps may not always be safe to
drink
Source: World Health Statistics, 2011
•
Diarrhoea is the 2nd leading cause of death among
children; About 4 lakh children die in India due to
diarrhoea every year, that is one child dies due to
diarrhoea every 80 seconds
Source: Diarrhoea: Why children are still dying and what can be done,
UNICEF/ WHO, 2009
•
88% of diarrhoeas can be prevented by safe water,
sanitation and good hygiene
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WHO Guidelines for Drinking water
quality - Water Safety Plans
The most effective means of consistently
ensuring the safety of a drinking-water supply is
through the use of a comprehensive risk
assessment and risk management approach
that encompasses all steps in water supply from
catchment to consumer.
The approach is called Water Safety Plan (WSP)
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What is a Water Safety Plan?
Water
resources &
sources
•
•
•
Treatment
Distribution
system
Consumer
system
A documented plan that:
– Identifies hazards, assesses risks from
catchment to consumer
– Prioritizes risks – with focus on highest risks
– Mitigates risks through control measures
Moving away from reliance on output monitoring i.e. measuring parameters in final water
Move into input monitoring - i.e. measuring
parameters which show that the system is working
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Hazard, Hazardous event & Risk
• Hazard is a biological, chemical, physical or radiological
agent that has the potential to cause harm
• Hazardous event is an incident or situation that can lead to
the risk - what can happen and how? (e.g. heavy rainfall)
• Hazard identification - Desk studies & Site visits
• Risk is the likelihood of hazards causing harm in exposed
populations including
– Specified time frame
– Magnitude of the harm – deaths, disease, financial cost
Why do we need WSPs?
Gideon, Missouri, 1993
Hazard (contaminant)
Salmonella
Hazardous event (cause)
Pigeons nesting on a water tank roof
Tank roof was not sealed and pigeon
faeces were washed into the tank
Salmonella bacteria got concentrated
in the sediment & the surface
During a flushing event, the bacteria
got rapidly drained into the distribution
system and chlorine residual was not
enough
Effect
~ 500 ill from a town of 1,104
7 Dead
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Why do we need WSPs?
Milwaukee, Wisconsin, 1993
• Hazard (contaminant)
– Cryptosporidium cysts
• Hazardous event (cause)
– Runoff from heavy spring rains
– Carrying sewage into Lake Michigan
(from which raw water was drawn)
– Coagulation problems on the filtration
system in the water treatment plant
• Effect
– 400,000 became ill from 1.2 million
– 100 dead
Source: Presentation of Mr Asoka Jayaratne, Water Quality Specialist
Yarra Valley Water,Melbourne, Australia
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Why do we need WSPs?
Walkerton, Ontario, 2000
Hazard (contaminants)
E. coli O157:H7
Campylobacter jejuni
 Hazardous event (cause)




Heavy rains
Cow manure washed into a well
Failure to chlorinate
Water supplied by local water utility
Effect
– 2,300 ill
– 7 Dead
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Why do we need WSPs?
• Recontamination in the
distribution lines and at the
household level
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Components of WSP (1/3)
1. A system assessment to
determine whether drinking-water
supply chain as a whole can deliver
water of a quality that meets
requirements.
Components of WSP (2/3)
Identifying control measures in the system that
will control identified risks and ensure that the
health-based requirements are met.
For each identified control measure, an
appropriate means of operational monitoring
should be defined that will ensure that any
deviation from required performance is rapidly
detected.
Components of WSP (3/3)
Management and communication plans
describe actions to be taken during normal
operation or incident conditions and documenting
the system assessment, including upgrade and
improvement planning, monitoring and
communication plans.
Step-by-step risk management
1.
2.
3.
4.
Assemble the WSP team
Describe the water supply system
Identify hazards and hazardous events and assess the risks
Determine and validate control measures, reassess and prioritize
the risks
5. Develop, implement and maintain an improvement/upgrade plan
6. Define monitoring of the control measures
7. Verify the effectiveness of the WSP
8. Prepare management procedures
9. Develop supporting programmes
10. Plan and carry out periodic review of the WSP
11. Revise the WSP following an incident
In simple terms, WSP means:
1. What
are the
risks?
3. How do we
know the risks
are under control?
Continuous
Cycle
2. How do we
control the
risks?
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Describe the water supply system
•
•
•
•
•
•
•
•
Source of water
Changes due to weather
Details of land use in the catchment
Water storage
Water treatment (processes and chemicals)
Storage, distribution network
Availability of trained staff
Quality of documentation
Risk assessment
Likelihood Score
• Almost certain (once a day)
5
• Likely (once a week)
4
• Moderate (once a month)
3
• Unlikely (once a year)
2
• Rare (once every 5 years)
1
Severity Score
• Insignificant / No impact
1
• Minor compliance impact
2
• Moderate aesthetic impact
3
• Major regulatory impact
4
• Catastrophic Public Health impact 5
Likelihood score x Severity score = Risk score
Verify the effectiveness of the WSP
Treatment works
• pH
• Chlorine dosing records
• Residual Chlorine
• Turbidity
-
Daily
Weekly
Daily
Daily
Distribution system
• pH
• Chlorine levels
• Turbidity
• Sanitary inspection
-
Weekly
Weekly
Weekly
Weekly
Why do we need WSPs now?
• Increasing risks of water quality –
microbiological as well as chemicals from
industrial and agricultural activities (pesticides
and fertilizers)
• Increased awareness among consumers on the
need to have safe water
• Outbreaks (in many countries) - due to
(re)contamination of water, after treatment
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Status of WSP implementation
• WSP piloted in over 40 urban and 100 rural
supplies in Asia - Bangladesh, Bhutan and Nepal
• WSP piloted in Hyderabad and Nagpur municipal
water supplies in India
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Outcomes of WSP:
Improved water quality
• Water source protection and preservation
• Small problems are identified early and fixed,
preventing bigger problems
• In water systems where WSP is carried on a
continuous basis (24 x 7), water is found to be
safer to drink with microbiological test results,
before and after WSP, showing dramatic
improvement
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Outcomes of WSP:
improved management
• Standard operating procedures improved
• Clear roles and responsibilities
• Regular monitoring of water quality in treatment
•
•
plants
Promotes conversion to 24x7 supply
Reduction in non-revenue water
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Conclusion
• Water safety plan ensures water safety
(improves health) and sustainability of
drinking water supplies
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Thank you
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