Blue or green looking water is often due to the presence of new copper pipework, either in new houses or where new pipework has been installed in older properties. This is because these new copper pipes are settling in.
To help prevent this from happening, take the following steps:
Only use lead-free flux
Flush through new pipework thorougly
Drain down plumbing systems which are not used immediately after installation.
Blue water can also be caused by poorly installed toilet cisterns, which allow water from the cisterns to siphon back into the internal plumbing.
For information about how to check your toilet cistern please visit the WRAS website.
If your water is blue please do not drink the water or use it for cooking until you have sought advice from your water supplier.