How to Unblock a Drain

Unblocking drains including toilets, showers etc. can be a relatively easy, but still dirty job. The key here, as with 99% of jobs in the building and DIY world, is to have the right tools. It is also necessary to wear a very good pair of rubber gloves. We will not go into the diseases toilets and waste pipes can carry, but trust us, you do not want any of them!

A sink, bath, basin and shower tray can be unblocked in a few ways. An ordinary plunger can be used by placing it over the plug hole and pushing up and down on the handle. This creates a force in both directions, compression as you push down and suction as you release. The idea here is that the blockage is dislodged and breaks up allowing it to flow down the drain. The plungers we recommend for this are below.

For an easier way to unblock sinks etc…. you can now use what is known as a power plunger. This (above centre) tool is simply "pumped up" by pumping the handle at the end and placed over the plug hole. By pressing the trigger all the compressed air is released, forcing the blockage down the pipe or breaking it into bits.

Our personal favourite at Diydoctor is the one above, the water injector. Put some water in the sink, basin, bath or shower tray and stand the pump in it. Pull up on the handle to fill it with water. Then place it over the plug hole and push down hard, then pull up again etc etc. The water is pushed at great force through the blockage, and then by sucking up again, the forces explained in the first example with the plunger are put into operation. If your blockage is within a couple of meters of the plug hole, this little beast will clear it.

Finally, for sinks, basins, baths and showers, there is the corkscrew cable. The flexible wire is pushed into the drain pipe, wiggled about to break up the blockage, and wound back in. Very simple, very effective.

For unblocking toilets, the black toilet plunger above is the tool to use if you think your blockage is in the U bend at the back of the toilet. The action is exactly the same, push and pull to break up the blockage. For blockages which appear to be further down it may be necessary to open the manhole to inspect and clear.

You may have a visible soil and vent pipe (SVP) coming out of your bathroom which you can follow down to the ground and look around for the nearest manhole to it. It may not be the one and further checks may be needed. There are two types of manhole for the purposes of this project. The surface water manholes which collect water from your rain gutters, and the foul water manholes which collect the waste water from the sinks, basins, baths, showers and toilets.

These will smell so identification should not be too much of a problem. Although your toilet may be blocked there is a chance that some seepage is occurring through the blockage and you may need to identify this to see which manhole it is running into. This can be done by adding a little dye into the water and watching at the various manholes to trace the flow.

Once you have traced the manhole or manholes you may well be able to rod back up towards the house. Drain rods come in lengths of one meter and are screwed together to make a long length. They are very flexible and are simply inserted into the drain pipe and pushed into the run. You will feel when you meet a blockage and you should then prod the blockage with the rod.

Drain rods come with various fittings to screw on the end which, in theory, make the removal of blockages easier. We always start with nothing except the rod, prodding and poking until the obstacle (usually loads of toilet paper or nappies) clears. Occasionally we have had to use a worm screw (this comes with the set).

Sometimes you may not feel a blockage as it is either too far or too soft to register. Then its time to screw on the rubber plunger. Use the rods then as a giant plunger, pushing and pulling up and down the pipe. This will create the same pressures again as mentioned above and release the blockage.

The diagram above represents the basics of what you will find in a manhole. Usually a brick built structure (modern manholes are sometimes formed with precast concrete rings) with a sloping floor called benching, which slopes down into a half pipe shape called a channel.

After carefully removing the manhole cover which can sometimes be very heavy, the rods should be screwed together one at a time and pushed into the drain pipe. Sometimes if your pipe is well blocked, the channel and benching may be covered in water making the drain hole difficult to see…. Poke around with the rod until you find the entrance.

A word of warning: some manholes can be quite deep. These manholes are normally fitted with iron steps built into the sides of the brickwork or concrete. This is obviously for climbing down… BUT; manholes are very dangerous places as the gasses they contain can be overpowering. Do not go down into a manhole without someone at the top to make sure you are ok…. Sounds very silly in your own back garden, but professional builders have drowned in manholes because they were overcome by the fumes.

Very occasionally you will meet a blockage which cannot be reached from the toilet end or from the manhole end. This means it may well be in the soil and vent pipe itself. Most of these will have access plates, which should be undone very very carefully for obvious reasons. A lot of SVP’s will be boxed in and this can cause real disruption. If you cannot unblock the drain/pipes etc by your self and you feel you have established that the blockage is in your SVP then I’m afraid it may be time to call a plumber. The mess that can be created by this kind of blockage is something you really do not want to deal with if you are not sure of what you are doing.

One last word of warning. Drain rods will screw together in a normal clockwise way. When you are rodding a drain, the rods will turn in your hand, its impossible to stop them….Make sure you deliberately turn the rods as you push and prod and make sure you are turning them clockwise. If you do not do this, and without you realising the rods are slipping anti-clockwise in your hands, they can undo themselves.

Leaving a length of drain rod in your waste pipe will not help your blockage we can promise you that.

Why not check out our video section on unblocking, plumbing tips and plumbing unblocking to watch various films that will show how to unblock either a sink or drain.