10 Common Causes of Blocked Drains and How to Fix Them

10 Common Causes of Blocked Drains and How to Fix Them

Blocked drains can occur any time of the year, but some blockages can be seasonal due to lifestyle and temperature changes.

If you have a blocked drain, you need to know what type of drain it is. Is it sewer or storm water?

The blocked drains which cause the most concern and inconvenience are those inside the home when using the fixtures in the kitchen, bathrooms and laundry. These will be connected to your sewer.

Major pipe blockages will require the expertise of a plumber to remove the obstruction. You may also be able to prevent the blockage from occurring with a few maintenance tips.

Here are some of the causes of blocked drains in the home and what you can do to fix them.

10 Common Causes of Blocked Drains

10 common causes of blocked drains in a home and how to fix them

1. Tree Roots

One of the most common causes of blocked drains is tree roots.

Tree roots will penetrate a waste pipe if there is a crack in the pipe or if the root system is strong enough to break through the pipe.

Some plumbers argue tree roots can’t cause the break and the pipe must have been broken prior to the penetration. Either way, tree roots are bad for pipes.

This type of blockage is common in homes with large trees on or near their property.

The only way to fix the blockage is to use a jet rodding machine. If the drain needs to be fixed, excavation and relaying of the pipe will be needed. Depending on the break, the pipe may be internally relined without the need for excavating.

A drain camera will give a clearer picture on the best way to fix the problem and prevent the blockage from occurring again.

Ideally, removing the tree to prevent the roots from growing is the best course of action. Sometimes it’s not possible though if the tree is protected by the council. In this instance, you may need to organise a yearly drain clean and inspection to prevent an unexpected blockage.

2. Fats and Food

Fats and food are notorious for causing pipe blockages, especially in winter.

Always dispose of food scraps in the bin, not down the drain. Foods like rice and pasta swell in water and can cause a blockage to your sink.

Fats are also not good news to your drains or the shared sewer network.

‘Fatbergs’ are the solidification of oils and fats which have been rinsed down the sink to create a mass in the drain. When fats enter the sewer, the winter temperatures cause the fats to solidify and they meet up with wipes and other solids to create a large scale fat mass.

These fatbergs are obstructive to our sewers and can cost millions of dollars in removal and maintenance to our waste management systems.

To prevent a fatberg from building up, don’t rinse fats and oils down the drain. Allow them to solidify and scrape them into the bin.

Alternatively, for rinsing plates with little remnants of oil, be sure to rinse with hot water. Dishwashing liquid will disperse the minor oil residue when it enters the drain.

If you suspect your sink drain is blocked from fat residue, pour boiling hot water and dishwashing detergent to break up the fat. You can also try bi-carb soda and vinegar with this natural cleaning remedy.

3. Wipes

As the saying goes, only pee, poo and toilet paper (and puke!) should be flushed down the toilet.

Unfortunately due to mass buying of toilet paper, there has been an increase in use of flushable wipes and paper towels. This was a problem before COVID19 hit our shores due to poor packaging advising they could be flushed.

If you resort to using wipes or paper towels, bin them, don’t flush them. Toilet paper disintegrates in water. Wipes and paper towel soak water and can cause a major blockage to your toilet and further down the drain from your property.

4. Small Solid Objects eg Toys

Flushing small solid objects down the toilet is preventable, but with kids, it can sometimes be inevitable.

Kids like to be curious and you can’t have your eyes on them 24/7.

If you know your child has flushed a toy down the toilet, there is no reason for alarm as it may travel through your drains with no harm.

But if the bowl fills up after a flush or you notice the fixtures won’t drain water, it’s caused a blockage.

A jet rodding machine will be the only way to blast the blockage. An electric eel or drain snake may be able to retrieve the item back… if your child even wants it back after being immersed in effluent.

5. Hair

Shower blockages are commonly caused by hair. An accumulation of hair, mixed with shampoos and conditioners can create slurry at the bottom of the drain and cause a blockage.

The use of a drain cleaner with sulfuric acid will eat away at this slurry and clear your shower drain. A sani-snake can also clear away the obstructive mass.

To prevent hair from going down the drain, don’t force it down the drain after washing hair. Retrieve the strands and place in the bin.

Alternatively you can add in a shower hair strainer to the floor grate.

6. Soap slurry

Soaps made from fats can create a sludge at the bottom of the drain. When they mix with hair and other human waste, they can cause a blockage to the fixture.

Bicarb soda and vinegar is a natural way to clear this type of blockage. Use 1/3 cup of Bi-Carb Soda and pour ½ cup of vinegar. Alternatively a jet rodding machine can give the drains a thorough clean to prevent a buildup and potential blockage in the future.

7. Concrete or tiler’s grout

A concrete or tiler’s grout blockage is common on renovated or new build bathrooms. It’s a difficult blockage to remove without the right equipment.

The best way to prevent it is to cap waste outlets when the tilers come to grout the shower tray. This can prevent the grout being disposed of down the waste.

A jet rodding machine, with the use of drain cleaning products, can remove the blockage.

8. Back-fall of drain pipes

Occasionally, ground movement or sometimes poor installation of drains can be the root cause of constant blockages. Waste pipes need to have fall to allow for waste water to flow. If there is a flat line or back-fall, blockages are inevitable.

A drain camera is the best way to identify where the drain has back-fall or has a belly (dips down and then up) and a plumber will have to quote on the cost to replace this section of pipe. It may be costly, but so can constant call outs to clear blockages.

9. Sanitary products

Sanitary products like tampons and pads should always be disposed of in the bin provided and never flushed down the toilet.

These items cannot disintegrate in water and can ravel around other solds in the sewer causing a major blockage.

Always provide a bin in the toilet for these items to be disposed of. Without a bin, they will end up flushed down the toilet.

10. Incorrect waste connections

Another common cause for a pipe blockage is the incorrect installation of waste pipes. This is due to drains being installed by an unlicensed tradesperson.

You cannot expect a free flowing toilet when the 100mm waste has been reduced down to connect to a 40mm pipe connection. There are bound to be blockages and a few curse words from the plumber called up to rectify it.

Pipe connections will always connect to a larger diameter, never to a smaller diameter. The moment this type of installation is identified, it needs to be rectified by a licensed plumber, immediately.

These common causes of blocked drains are bound to happen on your property at one stage or another. Hopefully these tips will help prevent them from occurring, or at least give you confidence on how to get them unblocked.

If you enjoyed this post, you may want to read

What is a blocked ORG and what does it mean for your property?

Toilet Paper Alternatives – What to do when the shelves are bare?


Disclaimer: The information is intended to be of a general nature only. I do not accept any legal responsibility for any loss incurred as a result of reliance upon it – please make your own decisions and enquiries. Always use a licensed plumber for your plumbing needs.