Usually air. The Drinking Water Inspectorate says: “White or cloudy water is normally caused by tiny air bubbles trapped in the water, usually when the water has been turned off nearby.” “This can be easily checked by pouring water into a glass and watching it clear from the bottom up.”
Source: Drinking Water Inspectorate, White or Cloudy Water ↗
What to do
“If the problem has been present for less than 24 hours, run the tap to help clear the water. If it does not clear, or you notice an unusual smell or taste to the water at the same time, contact your water supplier for further advice.”
“Cloudy water is normally short lived and should normally clear within 24 hours.”
Source: Drinking Water Inspectorate, White or Cloudy Water ↗
If it keeps happening
When cloudy water lasts longer, the regulator lists causes in your own plumbing:
- Cold water pipes can sometimes be warmed by heating or hot water pipes
- The external or internal stop tap may be partially shut
- You may have an aerator fitted to the tap
Source: Drinking Water Inspectorate, White or Cloudy Water ↗
Is cloudy water harmful?
“White or cloudy water is likely to be caused by air trapped in the water and is not harmful to health.”
Source: Drinking Water Inspectorate, White or Cloudy Water ↗
Contact your water company
If the water does not clear, or it smells or tastes unusual, contact your water company.
Find your water company from your postcode
Related pages
Sources
- Drinking Water Inspectorate: White or Cloudy Water ↗ · Open Government Licence v3.0 · read 14 October 2026
Contains public sector information licensed under the Open Government Licence v3.0.