cistern filling when basin tap turned on??

[novicejon]

A friend has told me her cistern is filling when she turns her basin taps on. Anyone know what could be causing this??

 

[REDSAW]

not entirely sure but, it could be cold water.

 

[WHPES]

I assume you mean the cistern in the loft.

If you are on a vented system, then the hot basin tap should cause the cistern to top up as you use water.

Some bathroom cold water comes from the cistern too.