How to Clear a Blocked Sink
How to Clear or Unblock a Sink or Basin
Don’t ignore the early signs of an imminent blockage of the wastepipe from a sink or basin — it only gets worse. If the water drains away slowly, use a proprietary chemical drain cleaner to remove a partial blockage before you are faced with clearing a serious obstruction. Regular cleaning with a similar cleaner also keeps the waste system clear and sweet-smelling. If a wastepipe blocks without warning, try a series of measures to locate and clear the obstruction.
- Sink plunger
- Hydraulic pump
- Adjustable wrench
Cleaning the Waste-Pipe and Trap
In most cases, blockages occur because grease, hair and particles of kitchen debris build up gradually within traps and wastepipes. If water drains away sluggishly, use a cleaner immediately. Follow the manufacturer’s instructions carefully, with particular regard to safety. Always wear protective gloves and goggles when handling chemical cleaners, and keep them out of the reach of children.
If unpleasant odours linger after you have cleaned the waste, pour a little disinfectant into the basin overflow.
Using a plunger
If one basin fails to empty while others are functioning normally, the blockage must be somewhere along its individual branch pipe. Before you attempt to locate the blockage, try forcing it out of the pipe with a sink plunger. Smear the rim of the rubber cup with petroleum jelly, then lower it into the blocked basin to cover the waste outlet. Make sure there is enough water in the basin to cover the cup. Block the overflow with a wet cloth, held in one hand, while you pump the handle of the plunger up and down a few times. The waste may not clear immediately if the blockage is merely forced further along the pipe, so repeat the process until the water drains away. If it will not clear after several attempts, try clearing the trap.
Now clear the trap
The trap, situated immediately below the waste outlet of a sink or basin, is basically a bent tube designed to hold water that seals out drain odours. Traps become blocked when debris collects at the lowest point of the bend. Place a bucket under the basin to catch the water, then use a wrench to release the cleaning eye at the base of a standard trap. Alternatively, remove the large access cap on a bottle trap by hand. If there is no provision for gaining access to the trap, unscrew the connecting nuts and remove the entire trap.
Let the contents of the trap drain into the bucket, then bend a hook on the end of a length of wire and use it to probe the section of waste pipe beyond the trap. (It is also worth checking outside to see if the other end of the pipe is blocked with leaves.) If you have to remove the trap, take the opportunity to scrub it out with detergent before replacing it.
Another way to clear the branch pipe
Quite often, a vertical pipe from the trap joins a virtually horizontal section of the wastepipe. There should be an access plug built into the joint so that you can clear the horizontal pipe. Have a bowl ready to collect any trapped water, then unscrew the plug by hand. Use a length of hooked wire to probe the branch pipe. If you locate a blockage that seems very firmly lodged, rent a drain auger from a tool-hire company to clear the pipe.
If there is no access plug, remove the trap and probe the pipe with an auger. If the wastepipe is constructed with push-fit joints, you can dismantle it.
The last resort
If a plunger is ineffective in clearing a blocked waste outlet, use a simple hand-operated hydraulic pump. A downward stroke on the tool forces a powerful jet of water along the pipe to disperse the blockage. If it is lodged firmly, an upward stroke may create enough suction to pull it free.
Block the sink overflow with a wet cloth. Fill the pump with water from the tap, then hold its nozzle over the outlet, pressing down firmly. Pump up and down until the obstruction is cleared.