Why roots get into pipes
Roots do not break pipes open. They follow moisture. A sewer pipe leaks a little water and nutrients through its joints, and that is enough to attract fine roots. They squeeze through the gap, then thicken.
Once inside, roots act like a net. Paper and fat catch on them. A drain that flowed well for decades starts to slow, then blocks.
Why older Mountains homes are at risk
Many older cottages have clay or terracotta sewer pipes. These come in short lengths, joined with cement or rubber rings. Every joint is a gap roots can find.
Ground movement on steep blocks, and the weight of old trees, can shift pipes and open joints further. Few older homes have an inspection opening, so a problem can go unseen for years.
Signs of roots
- A drain that blocks again and again in the same place
- Gurgling when you flush or run the washing machine
- Slow drains across several fixtures
- A damp or green patch on the lawn over the sewer line
- Sewage smell in the yard, or water rising in the outside gully
Roots can grow faster in wet weather and in spring, so the first blockage often shows up after a long wet spell.
Your options
There is no single fix. The right option depends on the pipe, the roots and the tree.
- Cutting roots out of the pipe with a machine or a jetter clears the line, but roots regrow. How soon depends on the tree and the pipe
- Repairing a cracked or displaced section stops roots getting back in at that spot
- Pipe relining puts a new lining inside the old pipe and seals joints. Ask whether it suits your pipe. See pipe relining
- Replacing a failed section by digging is the last resort, and may be needed if the pipe has collapsed
- Removing or managing the tree is a council or owner decision, and you may need approval first
A drain camera can show where the roots enter and how bad the damage is. Ask whether it's needed for your job. See CCTV drain inspection.
Who is responsible
Sydney Water looks after the sewer main. The pipe from your house to the main is the owner's job, even when the tree that caused it is on the street. Councils have their own rules for street trees, so check before you do anything to one.
If the blockage sits in the main, call Sydney Water. The plumber can help you work out where it is.
What it costs
Root jobs vary a lot. A short blockage close to the house is a different job from a long run under a driveway. Ask for a quote before work starts. If a repair or relining is needed, ask for the options in writing.
Keeping roots out
- Know where your sewer line runs before you plant
- Keep thirsty trees well away from the line
- Have a repeat blockage checked early, not after the third one
- Fix cracks and loose joints when they are found, before roots settle in
Blocked drain in the Blue Mountains?
Call 0495 053 644Tree roots in drains questions
Do roots always mean I need a new pipe?
No. Some pipes only need the roots cleared. Others have cracks or shifted joints that will keep letting roots back in. A camera view helps you choose.
How often do roots grow back?
It varies with the tree, the weather and the pipe. Some lines are clear for years. Others block each season.
Can I use copper sulphate or rock salt?
Take advice before you use anything. Some products can harm the environment, and they do not fix a cracked pipe.
Can I just cut down the tree?
Not always. You may need approval, and cutting a tree does not remove roots already in the pipe. Ask your council first.
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