Mr Patsy McGlone (Mid Ulster): To ask the Minister for Infrastructure to detail (i) the mechanisms used by NI Water to measure the level of microcystins in the public water supply; and (ii) how often the measurement is taken at each water treatment plant, over the course of a year.
Minister for Infrastructure: The issue you have raised is an operational matter for NI Water; however, I have sought the required information.
(i)NI Water has advised that it uses the Drinking Water Safety Plan (DWSP) approach to assess the risk for Microcystins in the public water supply. The DWSP approach is based on the World Health Organisation’s Water Safety Plan guidance and is used to systematically assess and manage drinking water quality risks from the catchment and raw water source to the customer tap. NI Water has developed an in-house method for the analysis of Microcystins, based on the industry standard Standing Committee of Analysts method. This method provides NI Water with a rapid, sensitive, and reliable analytical method for the measurement of microcystin’s in the public drinking water supply and also to monitor the risk in the raw water and the performance of the multibarrier treatment barriers in place at the WTW.
(ii) NI Water has advised that sampling and analysis programmes for Microcystins are based on the DWSP risk assessment for each Water Treatment Works (WTW). This is kept under review in line with the DWSP risk assessment and sample numbers increased when required. Raw and treated final water samples are tested at least fortnightly at water treatment works where there is a potential for algal blooms to occur in the raw water source. For sites where the risk is greatest the frequency of testing is increased to at least weekly, with some sites such as those that use Lough Neagh as the raw water source, sampled at least three times per week over the high risk period or when there are algal blooms reported.
For any future queries relating to operational matters, you should contact NI Water directly, through the Elected Representatives Hotline on 0345 300 6461 or through waterline@niwater.com .
Making direct contact with NI Water will ensure that you receive the information in the shortest possible timeframe and make best use of limited public resources.
ENDS
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