To provide water that's good for you, we have to meet the drinking water quality standards set by the Water Supply (Water Quality) Regulations.
The type of treatment process required depends on the type of raw water source and its quality in a particular area.
Water from springs and boreholes is generally higher quality and may only need basic treatment followed by disinfection. Water from sources such as rivers, lakes and reservoirs, will normally require more complex treatment as it may contain more impurities (for example, pesticides) that have to be removed.
We monitor the quality of our raw water sources to make sure they haven’t become contaminated – and also to decide which type of treatment to use for a particular source of raw water. Follow the link to find out more about how we monitor, test and maintain water quality.
The treatment process
Treatment of water depends on the source, so any particular water supply works may use one (or more) of the processes below. We don't add fluoride to water – find out about the natural levels that occur.