A blocked drain rarely gives much warning. One day the shower drains slowly, and the next there is water pooling where it should not be. Most of the time the cause is simple. Something went down the toilet or sink that should have gone in the bin.
The good news is that most household blockages can be avoided with a few habits. It also helps to know where your drains run and which fittings protect your home. This guide covers what to keep out of your pipes, the warning signs to watch for and when to call a plumber.
Why drains block in the first place
Household pipes are built to carry water, human waste and toilet paper. Toilet paper is made to break down quickly in water. Most other products are not. When they get caught in a bend or a joint, they slowly trap more waste until the pipe chokes.
According to Sydney Water advice on protecting your plumbing, wet wipes create up to 75 per cent of all blockages. Household waste flushed down the toilet can form clumps that block drains and clog wastewater pipes. A blockage can push wastewater back into homes, backyards and local waterways. It can also lead to an expensive plumbing bill.
What should and should not be flushed
Sydney Water sums it up as the three Ps. The only things that should be flushed are pee, poo and paper. Everything else belongs in the bin. That rule sounds strict, but it is the easiest way to keep a toilet running freely for years.
The NSW Government lists several common culprits that cause trouble. Most of them look harmless when they go down. Keep these out of the toilet:
- Wet wipes and baby wipes
- Paper towels and tissues, which do not break down like toilet paper
- Hair, which tangles and traps other waste
- Cotton buds
- Sanitary items, which absorb liquid and swell when wet
The NSW Government suggests checking the packet of any wipe for a flushable icon. If you are unsure, put it in the bin. Sydney Water notes that details of a new flushable standard are on the way. Until then, the bin is the safe choice for any wipe.
Keeping fats, oils and grease out of the kitchen sink
The kitchen sink is the other big source of trouble. Sydney Water says fats, oils and grease should never go down the drain. When they meet cool water in the pipes, they harden. They can then combine with wipes and other waste to form a solid mass known as a fatberg.
Sydney Water says the only things that should go down a sink are water and soap. Wipe greasy pans with a paper towel before washing them and put the towel in the bin. Let cooking oil cool, then pour it into a sealed container for disposal. Scrape food scraps into the bin or compost rather than rinsing them away.
If you are planning new custom kitchen cabinets, think about the space under the sink too. A small bin or a sealed oil container kept within reach makes good habits much easier. It is a small design choice that saves trouble later.
Tree roots and your garden
Not every blockage starts inside the house. Port Macquarie Hastings Council lists tree roots breaking into pipes as a main cause of sewer blockages. Roots can enter the pipes as a tree grows. The council advises against planting trees over sewer pipes for this reason.
HealthyWA also notes that some tree species have more invasive roots than others. Before you plant, find out where your sewer line runs across the yard. Your plumbing plans or a local plumber can help. Our landscape design tips are a good starting point for planning garden beds and paths around these services.
The overflow relief gully explained
Most homes connected to sewer have an overflow relief gully, sometimes called a gully trap. It is a grated outlet outside the home near an external wall. It is usually close to the kitchen, laundry or bathroom. Its job is to let sewage escape outside if the drain blocks, rather than backing up inside the house.
The Townsville City Council guide to overflow relief gullies explains how it should be set up. The grate should be loose so it can easily pop off. The gully must sit at least 75mm above the surrounding finished ground so water does not pond into it. It must also sit at least 150mm below the lowest drain in the building.
If the gully is not working, sewage can be pushed back up through floor grates, toilets or sinks. Common faults include the wrong height, downpipes draining into it and a grate that has been sealed down. Townsville City Council says connecting downpipes or stormwater to a gully is illegal and can lead to a council fine. Rules and fines are set locally, so check with your own council or water authority.
HealthyWA says the gully should not be covered by landscaping, garden beds, pot plants or paving. The grate should not be damaged or concreted in place. Keep leaves and other items clear of it too. A quick look during a weekend garden tidy is all it takes.
Warning signs of a blockage
Port Macquarie Hastings Council lists a few early signs. Gurgling noises from a sink, basins draining slowly or bad smells from drains may point to a blockage. These signs are worth acting on before the problem gets worse. A partial blockage can turn into a full one quite quickly.
Many properties have a vertical inspection shaft, usually near the boundary. The council says that if the shaft is empty, the blockage is within your property and you will need a plumber. If it is full or partly full, the blockage may be in the council network. In that case the council suggests reporting it before a plumber starts work.
Who is responsible for which pipes
In general, the water authority or council looks after the network up to the property connection point. Pipes and fittings on your side of that point are usually the owner’s job to maintain. Townsville City Council also says owners are responsible for drainage within their boundary, including any gully on the property. The exact split varies between councils and water authorities around Australia.
This matters when the bill arrives. Port Macquarie Hastings Council says it does not automatically pay a plumber’s bill for unblocking sewer pipes if it did not authorise the work. If you are unsure where the blockage is, call your council or water authority first. A short call can save a costly mistake.
When to call a licensed plumber
Plunging a sink or clearing a shower grate is fine for most people. Anything beyond that is best left to a licensed plumber. Townsville City Council suggests calling one if you cannot find your gully, if downpipes drain into it or if you suspect an illegal connection. A plumber can also check whether tree roots or cracked pipes are causing the problem.
A renovation is a good time to check the drains. Moving a toilet or basin changes how waste flows through the house. Our guide to common bathroom renovation mistakes covers other traps worth avoiding. If you are choosing eco friendly building materials for a larger project, ask your plumber about the condition of older pipes at the same time.
Frequently asked questions
Are flushable wipes safe to flush?
The NSW Government suggests checking the packet for a flushable icon and binning wipes if you are unsure. Sydney Water says wet wipes create up to 75 per cent of blockages. The safest choice is the bin.
Can I pour cooking oil down the sink with hot water?
No. Sydney Water says fats, oils and grease should never go down the drain. They harden when they meet cool water further along the pipes. Let oil cool and put it in a sealed container for the bin.
Where is my overflow relief gully?
It is usually outside near an external wall, close to the kitchen, laundry or bathroom. It has a small grate that should sit above the ground. If you cannot find it, a licensed plumber can locate it.
Who pays to clear a blocked sewer?
It depends on where the blockage is. Pipes on your side of the property connection point are usually the owner’s responsibility. Check with your council or water authority before booking a plumber.
This article is general information only. Plumbing rules and responsibilities differ between states, councils and water authorities. For problems with your drains, speak with a licensed plumber or your local water authority.
