NI Water managed to achieve a 99.9 per cent drinking water compliance rate in Derry and Strabane last year despite the serious flooding that struck its Carmoney supply station on the Faughan last August.
The firm’s annual report for the area for 2017, which was presented to the Derry City & Strabane District Council Health and Community Committee this month, showed tap water complied with all the physical-chemical and microbiological standards laid down in the Water Supply (Water Quality) Regulations (Northern Ireland) 2007.
It acknowledged, however, that the floods of August 22, 2017, did create problems for NI Water in what was described as the company’s only “serious event” of the year.
“Extremely heavy rainfall caused a series of flooding events in the North West. Carmoney Water Treatment Works (WTW) was off supply for five days, following flood damage to the raw water pumping station and there were eight burst mains. Water supply was maintained to customers through implementation of the WTW contingency Plan,” the report states.
The floods sparked a further “significant event” with heavy and light metal exceedences and excessive cloudiness in water supplies in the days that followed as NI Water made changes to cope with the supply cut-off.
“Aluminium, iron, manganese and turbidity contraventions were reported in the Carmoney WTWs final water.
“Our assessment is that the contraventions were related to disturbance caused by the operational activities regarding the rezoning of Ballinrees and Caugh Hill WTWs to maintain supplies and not due to the quality of water leaving the water treatment works,” the report adds.