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Steps to successfully unblock a sink

The easiest and most effective way to unblock most sink blockages is by using a simple plunger so try this first.

But are you using the plunger to its greatest effect ?

Unblocking a sink

Step 1    If the sink has no water in it first fill it with around 3 inches (7.5cm) of water.  (This amount optimum not  critical. Too much can cause you to get splashed but too little impedes the time suction effect.)

Step 2     This step is often overlooked. Block off any overflows with your hand or a wet dish cloth. If any overflows are not blocked then much of the suction generated by the plunger will be lost by pushing and pulling the air through the overflow. If you have a double sink, fit the plug into the sink you are not plunging and pour about 5 cm (2") of water into the sink to stop the plug becoming displaced during the plunging process.

Step 3     Start by slowly pushing and pulling the plunger over a short distance and keep plunger in contact with the sink. Build up a rhythm as you increase speed for a minute or so and see if the sink drains any quicker. You can repeat if there is improvement but it still drains slowly. If not you can move on to step 4

Step 4    This is the most effective way of plunging but it can cause a fair degree of splash. Ideally  use another person to block off any overflows so you can hold the plunger with both hands. Push down on the plunger and then pull up as sharply and quickly as you can. You need not travel a great distance, once the plunger has left the water the plunger obviously has no effect.

Using chemical drain cleaners

Most household chemical sink cleaners use a combination of sodium hydroxide (caustic soda) and surfactants ( a type of detergent) to clear the blockage. They make use of a reaction which turns fat into soap on contact with sodium hydroxide. The detergent is used to help wash any debris away. Obviously if the blockage is caused by a thick layer of accumulated fat this may take numerous attempts or may not even work at all. Likewise if the blockage is caused by something other than fats.

 

Even if the chemical cleaner is unable to unblock the sink on its own, it is still useful as it can often break down the blockage and enable it it be removed by agitation using a plunger.

 

Some commercial sink unblockers use strong acids (usually Sulphuric Acid.)  This strong acid dissolves any organic material such as food reside, fats and even hair and allows it then to be flushed away. The reaction also causes a large amount of heat to be produced which also helps dissolve waste material. To be effective the acid used is extremely powerful and it requires careful handling and the use of eye, lung and body protection.  If the acid comes into contact with any metal such as a stainless sink or a sink outlet it will permanently damage it.  It is therefore usually applied directly into the water pipe. Due to the risks involved it is not generally suitable for unblocking waste pipes in domestic settings but there are situations where its use may be appropriate.

Tip !  It can often be effective to loosen the blockage using a chemical unblocker or bleach to loosen the blockage first. If you decide to do this protect your eyes and clothing from any splashes while plunging.

Remove the sink trap and manually remove the blockage

Tip !    For extra plunging power, if you have a washing machine or dishwasher pipe connected to the trap block them off by means of a clamp to the pipe, bending it back on itself and tying up. Or if you are confident enough, remove the nut retaining the pipe to the trap,  put a small coin wrapped in polythene into the nuts and re-attack the nuts.

Most kitchen sinks are fitted with a "S" or "P"  type trap, the only difference is the outlet position which governs its shape. Most basin sinks will be fitted with a bottle type trap but you also find them fitted to kitchen sinks.

sink with bottle trap

Twin sink with manifold directed to a single bottle trap. (lowest part of the fitting in grey)

Twin sink with S type trap

Under your sink may look nice and neat like this twin manifold to "S" type trap.

under-twin-sink with S trap

Or it may look a bit more complex like this "P" trap configuration

Either way the important thing is to locate the "S"  or "P" trap, remove it by undoing the retaining nuts and cleaning out any debris blocking it. Don't forget to place a container under the trap before you remove it to catch the waste water contained in it.

Cleaning a bottle type sink trap.

Cleaning out a bottle trap is more straightforward. The bottom portion og the trap is simply screwed from the upper section and any accumulation will be visible and easily emptied from the trap.

If the blockage is not in the trap or the surrounding pipework then you main to call a plumber. It is always worth trying a combination of a sink unblocking chemical and plunger first or even one of the flexible wire type of unblockers available.

Tip!   Sink traps are not costly and you may wish to take this opportunity to replace the trap while it is removed. An old sink trap will be pitted and more likely to trap dirt and block than a new smooth surface on a replacement trap.

 

There are various kinds of sink plungers on the market such as this selection from the Amazon site.  When using the piston type of plunger such as the one to the  far right, ensure your plumbing is in good, tight condition as the force may displace any loose connected pipes.

Strong caustic soda solution  is the traditional first port of call for chemically unblocking a sink.

Strong acid cleaners like this are very effective but pour into the trap, do not pour directly into the sink or you will most likely damage your sink or outlet. Ensure you have the safety equipment and skills in place before you contemplate using it.

IMG_20180826_205701 (2) IMG_20180826_210553 (2) IMG_20180826_210915 (2) Single bowl bottle trap

A single sink, bottle trap.

Once the trap is removed separate the two parts by loosening the nut. Take care not lose the seals on the joints. The trap can now be cleaned out.

Cleaning an "S" or "P" type trap

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