Last updated: February 2024

Water Quality FAQs: Appearance of water

Why is my water a shade of blue?

Clean water will naturally have a blue hue to it. Water which has a definite blue or turquoise colour as opposed to hint, is often due to new copper pipe work or the use of poor quality brass fittings. To help prevent this from happening new pipe work needs to be thoroughly flushed, which may need to be repeated over a period of weeks until the pipework stabilises, and make sure brass fittings are manufactured from appropriate materials.

Another source of intense blue water may be water siphoned back via inlet valves supplying toilet cisterns. Where the inlet to toilet cisterns is installed incorrectly water coloured by a toilet block (the colour of the water will depend on the colour of the toilet block used, if this is the issue) can be back siphoned into the plumbing system.

If you suspect you have elevated level of copper or water back siphoned from a toilet block, please contact your water undertaker for advice.



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Uncontrolled if downloaded. This is informative, non-statutory guidance and intended for general guidance purposes only; it is subject to change.

Compliance with this information should not be relied upon as guaranteeing no enforcement action will be taken by water undertakers. Water Regs UK accepts no liability for loss, indirect or consequential loss arising from or in connection with this guidance document.

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