Why is my water blue or green?

Blue or green water is sometimes caused by the formation of copper salts which dissolve in water when it passes through copper pipes, giving a blue or turquoise appearance. It commonly shows as a stain on fixtures and fittings, especially those made of enamel. The source of the blue water is normally through the use of copper pipes in domestic plumbing.

Another potential cause of blue water relates to the use of blue coloured disinfectant tablets in toilet cisterns. If the toilet does not have the correct plumbing it is possible for blue water to syphon out of the cistern into the domestic plumbing.

What should I do?

To confirm the issue is related to domestic plumbing, run the cold tap that is fed directly off the mains supply (this is usually the cold water tap in the kitchen), the water should clear with flushing. If the water clears with flushing this indicated the source of the discolouration is the plumbing system. Check the condition of your domestic plumbing. If it is old and starting to deteriorate, this will increase the chance of getting blue water. If you have had some recent plumbing work done, check that the plumber has not used a different metal pipe connected to the copper pipe work. This can cause a galvanic action leading to copper being dissolved. Check your water pipes are correctly earthed. Poor earthing can lead to electrolysis and copper becoming dissolved. If your boiler or hot water system has a sacrificial anode, check this has not fully corroded. It may need replacing. This will likely need the services of a plumber.

If the blue water is coming from your toilet cistern it will need repairing by a qualified plumber.

If the blue green colouration does not clear with flushing, you can check Service Announcements to see if there are any known issues nearby which may be causing the discolouration or alternatively please call us and we can investigate the issue.

Knapp Mill supply area

Customers who live in the Christchurch, New Milton, Lymington, New Forest, Ringwood, St Leonards and Beaulieu areas.

Periodically during the autumn/winter period and following heavy rainfall you may experience slight changes in the colour of your water supply. Rest assured it is completely fine to drink and use as normal.

Typically, this colour change is identified in bathtubs or sinks (when the water is deep against a white background) and described as being clear of particles but with a slight green/yellow colouration. This colouration does not clear by flushing it through your system by running your taps.

Find out more

Discoloured water