Toilet plumbing can’t really be anyone’s favourite repair or install. It is, however, absolutely necessary to have a fully functioning toilet! Yesterday I drove 1 hour up to the North Norfolk coast to pick up an emergency callout to a a holiday home that was ‘desperate’ to get their only toilet unblocked. if the flush doesn’t work you can always flush the pan’s contents with a bucket of water but if you have a block then you may be just left with slopping out the bucket!
Toilet blocks could either be that something is jammed in the u-bend of the pan itself or the soil pipe, that takes the effluent away from the loo, under, the house to the main sewer. There will be an inspection hatch outside where the pipe under the house can be rodded.
The toilet will also have a cistern, essentially a container for water, that is released into the pan to flush away the contents. The cistern will have a cold water pipe feeding it at mains pressure and a valve inside the cistern to switch off the water flow once the cistern is full and ready to flush again.
Modern toilets incorporate a built in overflow into the push button flushing mechanism Older installations will likely have an overflow pipe running outside to cater for any failure of the fill valve to switch off properly.
If your toilet is running continuously it could be that the flush mechanism can’t close properly or that the fill valve is not shutting off the flow of new water filling the cistern.
There are two mechanisms inside the toilet cistern. One is for refilling the cistern and the other for emptying the water into the pan. Both can be replaced for about £25 for the parts but it will require the removal of the cistern from the wall and pan to fit a new flushing mech.
There is a rubber donut where the cistern and the pan couples together. This can become dirty and disfigured and not recreate a good seal against flushing water escaping where the pan couples the cistern. Apply some silicone to the new donut to ensure a water tight fitting.