The drinking water we supply to our customers must meet legal quality standards.
These are known as Prescribed Concentrations or Values (PCVs for short) and indicator parameters.
We monitor the quality of water as it leaves our water treatment works and service reservoirs to make sure that standards are being met. We also measure the quality of drinking water as it reaches our customers.
The North West region is divided into 261 water supply zones. The water supplied to a zone is usually from one particular water treatment works or service reservoir. Water samples are taken at addresses selected at random from customers' taps within a zone to monitor water quality in the zone as a whole.
The samples are tested at our laboratories and the results compared with the required quality standards. All the test results are recorded on the Drinking Water Register.