Report outlines ‘serious’ water quality incidents

THREE ‘serious’ drinking water events which potentially affected thousands of customers across West Tyrone were identified at reservoirs locally during 2022.

A report on the issue compiled by Northern Ireland Water (NIW), called ‘Serious Drinking Water Quality Events in 2020’, was presented to a meeting of Fermanagh and Omagh District Council’s Regeneration and Community committee last night (Wednesday).

The incidents happened at the Derg Waste Water Works between May 10 and 18 last year, and again between August 16 and November 10, and also at the Glenhordial Waste Water Works, outside Omagh, between June 27 and July 6.

In the Derg, there were contraventions of the individual pesticide standard for MCPA, which is generally used in agriculture for the control of weeds on farmland.

MCPA is favoured because it is specifically designed to kill weeds without harming crops.

NI Water blamed this contravention on ‘insufficient treatment’, and a Regulation Notice was issued.

NI Water says it regularly detects high levels of MCPA in rivers and lakes and at abstraction points in many drinking water sources in Northern Ireland.

It added that the pesticide was removed in the water treatment process, leaving drinking water of a high quality standard.

Meanwhile, a contravention of the individual pesticide standard for MCPA also occurred at Glenhordial last year.

Here, there is a pesticide removal treatment in place which NI Water stated is normally effective at removing MCPA levels to below the regulatory limit.

However, in May and June last year, the removal treatment at Glenhordial was not fully operational.

The final incident happened at the Derg Waste Water Works between August 16 and November 10.

A contravention of the total trihalomethanes (THMs) parameter occurred in the works supply due to what was described as ‘insufficient organics’.

Trihalomethanes (THMs) are liquid by-products formed when the chlorine which is used to disinfect water in order to make it safer to drink.

NI Water said that the information contained in its report is based on planned samples at authorised supply points, and also from randomly sampling customer taps.