My water supply

Water quality standards

We pride ourselves on delivering some of the highest quality water to our customers.

On a typical day, we treat 330 million litres of water to make it clean and pleasant to drink. It’s then supplied to 500,000 homes and 36,000 business customers.

Each year we carry out thousands of tests on samples we have taken from treatment works, reservoirs and homes across the region.

Drinking Water Inspectorate

Find out more about our Regulators

Water quality reports

The samples are analysed in a laboratory to ensure they comply with drinking water safety standards.

Check your water quality zone report

To access the correct water quality report:

1. Find the water quality zone for your area 

2. Download the report from the Useful downloads section on the right-hand side of this page.

Find out what the terms mean
Find out what the technical terms used in the Water Quality Reports mean.

The name of the zone (e.g. Shavers End 2) and type of parameter (test) covered by the report.

The concentration or value is expressed in different units. Most of the parameters sampled are in milligrams per litre (mg/l) or micrograms per litre (µg/l). These are very small amounts. One mg/l is one part in 1,000,000 parts of water (or 0.0001%). One µg/l is one part in 1,000,000,000 parts of water (or 0.0000001%)

Prescribed Concentration or Value (PCVs)
These standards are set down in the Water Supply (Water Quality) Regulations 2000 in line with European (EC) requirements. They are the acceptable levels of certain elements, compounds or substances, which are allowed in drinking water. Usually, the PCV is the maximum-allowed level, or occasionally the minimum-allowed level.

Number of samples
This is the number of samples collected from the zone during a period of time, usually the previous 12 months.

Number of samples > PCV
This is the number of samples that has breached a parameter limit or PCV.

% > PCV

This column shows the percentage of results, which failed the standard for each parameter sampled. This is expressed as a percentage of the total number of samples for that parameter. For example, 2% shows that 1 sample in 50 failed. In most cases, you will see a value of 0, which demonstrates that the water has met the standard every time a sample was collected.

Maximum, mean and minimum
This demonstrates a summary of the results from the tests over the time period. The minimum, mean and maximum concentrations are shown. The < symbol shows that the value recorded was below measurable limits. The mean is calculated by adding up all the results and dividing it by the total number of tests for that parameter.