To ask the Minister for Infrastructure to detail (i) how NI Water’s sewage discharge data is currently collected; and (ii) whether any independent verification of that data takes place.

The management of public wastewater infrastructure is an operational matter for NI Water. However, I have sought the requested information from NI Water and have been advised as follows:

Sewage discharges are generally considered under 2 categories: (a) discharges that occur on a continuous basis from a wastewater treatment works (WwTW), when wastewater has been treated to a standard that is considered safe to return to the environment, and (b) discharges that occur on an intermittent basis from storm overflows when dilute wastewater is discharged direct to the environment.

(a) With regard to treated effluent discharges from WwTWs, that are required to meet the standards set out in discharge consents issued by the NIEA, NI Water employs an Operator Self-Monitoring scheme as agreed with NIEA and in line with other water companies in Britain. This includes NI Water collecting data on the daily volume of treated discharges at some larger WwTWs via externally verified flow measurement systems.

(b) To monitor and record intermittent spills from storm overflows, Event Duration Monitors are being installed across NI Water’s wastewater network over a multi-year investment programme. These measure the start and stop times when a spill is occurring allowing the number and duration of spills to be determined for a calendar year.

None of the data collected is independently verified.

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.