Professional plumbers rarely relish being called out to deal with a blockage. There are specialist drain clearance firms, but they can’t always be contacted quickly in an emergency — and their charges reflect what can sometimes be the unpleasantness of the job. Drain or waste-pipe clearance is usually well within the capacity of the householder, and there are certainly few more cost-effective do-it-yourself jobs about the house.
The outlet of the sink, usually the trap immediately beneath the sink itself, is the commonest site of waste-pipe blockage. Usually the obstruction can be cleared quickly and easily by means of a sink-waste plunger or force cup. This is a very simple plumbing tool obtainable from any do-it-yourself shop, ironmongers or household store. It consists of a rubber or plastic hemisphere, usually mounted on a wooden or plastic handle. Every household should have one.
To use it to clear a sink waste blockage, first press a damp cloth firmly into the overflow outlet, holding it securely with one hand. Then pull out the plug and lower the plunger into the flooded sink so that the cup is positioned over the waste outlet. Plunge it up and down sharply half a dozen or more times. Since water cannot be compressed, the water in the waste between the cup and the obstruction is converted into a ram to clear the blockage. The overflow outlet is sealed to prevent the force being dissipated up the overflow.
If your first efforts at plunging are unsuccessful. persevere. Each thrust may be moving the obstruction a little further along the waste pipe until it is discharged into the drain gully or the main soil and waste stack.
Should plunging prove unsuccessful you’ll have to gain access to the trap. Brass and lead U-shaped traps have a screwed-in plug at the base. With plastic U-shaped and bottle traps the lower part can be unscrewed and removed.
Before attempting this, put the plug in the sink and place a bucket under the trap: it will probably be full of water unless the blockage is immediately below the sink outlet, and the chances are that opening the trap will release it. Having done so, probe into the trap, and into the waste pipe itself. You can buy purpose-made sink waste augers for this purpose, but you’ll find that a piece of expanding curtain wire, with a hook on the end. can be equally effective.