A choked waste pipe from a sink, basin or bath is indicated by slow or non-running waste water when the plug is removed. The first thing to do to try and clear the blockage is to use a plunger. The ‘old fashioned’ plunger is a simple – yet effective – hemisphere of thick rubber attached to a wooden handle. There are also modern variations including hand-operated air compressors, but essentially they all operate in the same way. Hold a damp cloth firmly against the overflow outlet with one hand and, with the other hand, place the rubber cup of the plunger or compressor over the waste outlet (plug hole) and plunge down sharply on the handle a few times.
If plunging doesn’t clear the blockage, then it’s likely that a solid object is lodged in the trap (the ‘U’ shaped pipe under the sink). There are a number of ways to tackle this. Place a bucket under the basin or sink to catch the water. At the base of the trap, you will find a cleaning eye (use a wrench to release this) or a bottle trap on which the whole base unscrews. Let the contents of the drain fall into the bucket. Bend a hook on a length or wire – a coat hanger is ideal – and gently probe the section of pipe beyond the trap.
If the pipe is clear but the blockage is still intact, then it’s in the branch of horizontal pipe running to the soil stack or outside to the vertical wastepipe. You may have an access plug in the joint to the horizontal pipe: if so, probe again with the wire. If you have no access plug, or the blockage seems very firm, then you can rent a drain auger to clear it.