Comprehensive Risk Assessment and Risk Management is Effective Tool of Consistently Ensuring the Safe Drinking Water in Colombo Metropolitan Area and Their Suburbs

Abstract

Abstract: Colombo is the largest economic and tourist attractive city in Sri Lanka, situated geographically at 127 degree 30’ E longitude and 37 degree 00’ N latitude. The city is spread over 37.3 km2 and its present population is 5.6 million in Colombo district .City administration is governed by Colombo Municipal Council with sub units in suburbs of Colombo. The drinking water supply is managed by the National Water Supply & Drainage Board (NWS&DB). It’s responsible for operating water treatment plants, safe storage and distribution of drinking water to consumers. Quality of the drinking water is customer satisfaction, therefore to ensure the customer satisfaction, not only the treated water quality – SLS 614: 2013 – but also raw water quality has to be monitored within SLS 722: 1985.KelaniRiver is the main drinking water source for 80 % population from Colombo and this river provides 700,000 m3 /day raw water to the water treatment plants in Ambatale and Biyagama. NWS&DB continue monitoring the raw water quality of Kelani river taking samples of selected locations to test selected water quality parameters.The purpose of testing the water quality in production centres and distribution system is to supply good quality drinking water achieving economic development with a healthy nation. Therefore NWS&DB has laboratory network in Colombo district to test physical, chemical and microbiological parameters in potable water according to SLS 614: 2013. Around 600 numbers of samples are taken monthly from distribution system to ensure microbiological quality of the drinking water. Water quality monitoring is reactive attitude rather than preventive,field investigation revealed that any action and activity that is required to prevent or eliminate hazards.Therefore risk assessment, risk management and control measures are required to ensure the quality of drinking water to achieve health base targets..