Blocked Drains


In our homes we have different types of drains which serve different purposes:

*   “Black water” drains carry sewage from our toilets. This must go to either to a septic tank for processing or to a sewer (if you are on the government sewerage system).

*   “Grey water” drains carry washing water from our kitchen sinks, washing machines, showers and washbasins. Grey water should also go to a septic tank or a sewer.

*   Rainwater gutters, downpipes and drains carry away rainwater. This can be discharged into absorption pits, flood drains, roadside gots (drainage channels) or, as long as it is clean, to rivers or streams.

*   Backwash water from water filtration and water softening equipment usually contains the minerals we find in our water but in very high concentrations, this is best sent to an absorption pit so the ground can filter out the minerals and return the water to the water table.

It is important to note that:

  1. It is illegal to discharge black or grey water into rainwater drains, roadside gots, rivers or streams.
  2. Rainwater should not be discharged into a septic tank or sewer. If, after heavy rain, you find your septic tank is overflowing you may find that someone has connected the rainwater drains to the septic system.



In The Past

It used to be that the most common cause of blocked drains were tree roots growing into rainwater drains and sewers and blocking them. In the past (and still used in Britain, Australia and other countries) external (underground) drains were made from ceramic pipes in which fairly short sections of pipe were connected using rubber ‘O’ rings to seal the joints. Inevitably a bit of ground movement or poor installation and a joint would start to leak, tree roots would follow the water, find the leak and grow into the pipe eventually blocking it. To clear such a blockage a special cutter attached to a rotating long coil spring (a snake) has to be pushed down the pipe to cut the roots and clear the blockage. If this doesn’t work the pipe has to be dug out and replaced.


Present Day

These days plastic is widely used for underground drainage pipes with sealed or welded joints. These don’t leak so tree roots rarely cause difficulties however blocked pipes are still a regular problem. Around our homes drains can become blocked by sand, soil, leaves, cement or other debris. This is common after floods or especially while a house is being built or renovated.

The most common cause, however, is a result of the many things we flush down toilets and sinks, it is the Black and Grey water drains that are most likely to get blocked.

Nappies (diapers), wet wipes, sanitary items, condoms and cotton buds cause the most problems. Most of these items are made from plastics and so they don’t break down. They can easily get caught in a joint or bend in a pipe and we have the start of a blockage.

Fats, oils and grease can also cause serious problems. As they cool down, coagulate or mix with other substances they may change their chemical structure (known as saponification) forming a soap like consistency which can be very difficult to remove.

Grease and fat is a particular problem for restaurants and cafes which is why they always install grease traps to collect grease before it gets into the drains.

Hospitals sometimes have problems with bathroom drains becoming blocked by body fat and soap.

Many blockages start by simply going to the toilet. Toilet paper “scrunchers” are people who use lots of toilet paper and scrunch it up into a ball which can block toilets. Folded toilet paper flushes away far more easily while water spray washers are best with no personal contact and no paper waste to flush down the toilet.


How to stop drains getting blocked

*   Do not flush wet wipes, nappies, diapers, condoms, sanitary products or cotton buds down your toilet.

*   Do not scrunch toilet paper into large balls, either fold it or, better, use water spray.

*   Do not pour cooking oils or fats down the kitchen sink.

*   Remove leaves from gutters downpipes and drains.

*   Do not let soil, sand or cement wash into drains.


How to protect yourself from blocked drains

*   Make sure you have a plumber or MEP engineer to design and advise you about black, grey and rain water installations.

*   Install “U” bends on floor and shower drains, washbasins, kitchen sinks, and bath drains. Toilets have “U” bends built into their design.

*   Make sure drains are a large enough diameter. 4 inch for toilets, 2 inch for grey water.

*   Make sure drains have sufficient slope for the water to run correctly.

*   Use round bottom rather than square bottom drains.This concentrates the water flow in the bottom helping to keep them clean.

*   Keep bends to a minimum and use 45 degree bends rather than 90 degree bends in underground pipework.

*   Install “cleanouts” in drains to allow access for pipe cleaning equipment.

*   In restaurants and cafes make sure you have a grease trap installed and clean it out regularly.



Chemical Drain Cleaners (or Drain Openers)

There are a number of chemicals available for unblocking drains which are acid or alkaline based. You pour the chemical down the drain, it dissolves the blockage to clear the drain. To work effectively they must have high concentrations of very nasty chemicals.

My advice is don’t use these very nasty chemicals, they are dangerous and can give serious burns, they can cause corrosion of metal pipes and fittings, they destroy the bacteria that make septic tanks work and are disastrous for the environment.


Plungers And Hand Pumps

The good old plunger (a rubber cap on the end of a wooden handle) can work well for small blockages in sinks, washbasins, toilets and floor drains. They may not fully remove blockages so blockages may reoccur. Plungers are low cost, easy to use and can give very useful temporary relief. Everyone should have one.


U Bends

Make sure you have U bends fitted to all washbasins, sinks, floor drains and shower drains. Toilets have them built in. U bends have two functions:

  1. They provide a water trap to stop bad smells or bugs coming from the sewer or drain.
  2. They catch things (anything from sand, nail clippings to wedding rings) that may fall into the drain.

Blockages are often caused by U bends becoming filled up. First try a plunger to see if that will clear it. If not then, with sinks and washbasins, you can remove the U bend, clean it out and replace it. With floor drains you may be able to remove the drain cover to clean out the U bend.

If all else fails call a plumber and make sure it is someone who knows what they are doing and has the specialist drain cleaning equipment needed.


Specialist Drain Cleaning Equipment

For more information on snakes, augers and other professional drain cleaning equipment see the full article at

If you are having trouble with a blocked drain and need help or advice, give us a call on WhatsApp +62 8123 847 852.


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