With all drain work it is sensible to wear rubber gloves for hygiene purposes. You should disinfect your hand and all equipment after completing the work.
If the water from a WC fails to drain away easily or, worse still, overflows completely, there is a blockage. Frequently this will be in the water trap in the pan itself and can readily be cleared.
But, before proceeding, check the flow from other waste pipes to establish whether the blockage is affecting all the pipes. If it is, then the obstruction will be further down the line. If not, carry on as follows.
Use a large plunger for this. Hold it so that the rubber end covers the waste outlet at the base of the pan and pump several times. Repeat as needed.
Once the blockage is clear, the waste water should flow rapidly away – it’s all downhill from here.
How to rod out the blockage
If this doesn’t clear it, the blockage may be further along, in which case, you can hire a large rodding auger to reach further along the pipework. This consists of a flexible rod which can be inserted. At the top is a mechanism for turning a claw at the far end using a winding handle at your end. Push the auger down the pipe until you feel it reach the obstruction. Then turn the handle to dislodge it.
If this fails to clear the blockage, it must be further along in the soil pipe or the drain run itself.
Unblocking a soil pipe
Old cast iron pipework rarely has serviceable access traps in it so the rodding out of such pipes may need to be undertaken via the vent, which is the top section on the roof. If this is the case, you may wish to consider employing a contractor unless you have sufficient skill and knowledge to access this pipe.
Access to this vent pipe will be high up and therefore potentially very dangerous. Never attempt to carry out such work without safe access equipment. It is not safe to stand a ladder against the pipe as no lateral stability will be offered and the pipe may well give way.
Fortunately, on modern plastic systems, access points are provided at pipe junctions.
Before unscrewing one of these, consider the consequences.
It is quite possible that there is a column of sewage sitting in the pipe above and this will come out at quite a speed. Unscrew it slowly and do your best to contain the result. If the pipework is indoors, lay plenty of plastic sheeting and make provision for clearing up the water.
Remove the access cover and insert a drain auger (available from hire shops). Feed the auger in until you feel it reach the obstruction.
Then turn the handle and move the auger back and forth to dislodge the blockage.
Withdraw the auger and flush the pipe with water from a hose. Replace the cover.