Discoloured water in a glass

Sometimes you may notice a change in the appearance of your drinking water. It may appear discoloured or have bits, stains or slime in it. 

Short term discoloured water can sometimes occur as a result of supply interruptions or burst water mains – find out if there has been any activity in your area

Discoloured water is caused by iron sediments which have settled inside the water mains over time. These sediments come from the cast iron water mains we have in our network. Normally this doesn’t affect anyone. But, a burst water main, for example, will increase the water flow and can stir up the sediment, causing the water to become discoloured.

Staining or slime on the the other hand is caused by airborne mould spores. These do not come from the water supply itself, but they like to grow in damp places.

The factsheets below explain the common causes of changes in the appearance of drinking water and what you can do to help: