Please can anyone help?
Recently our sinks upstairs and down have started to gurgle after we flush, or the washing machine empties, etc. we have been told that we should fit an anti vac valve.
Do I need to put an anti vac valve on every sink or just on the highest sink? I hope there is a simple answer as all our pipe work is hidden behind tiles (on walls and floors) and the traps are chrome!!!!
Thanks in advance.