Drain keeps blocking? Why it comes back and how to stop it

Why a drain keeps coming back — most likely first

1. Tree roots in an older pipe. Plenty of Melbourne homes still drain through clay or earthenware pipe laid in short sections. Roots find the joints, and clearing them cuts them back without closing the gap they came in through. They grow back, usually faster in the cooler months.
2. Displaced or cracked sections. When a pipe section drops or shifts, it leaves a step that catches paper, wipes and grease. Clear it and it works — until the step catches the next lot. On one Brunswick West job, the camera showed several dislodged sections holding water between joints, the classic recipe for a drain that blocks again weeks after every clear.
3. A sag or dip in the pipe. A section that has settled holds water and silt instead of draining, and builds up a blockage over time.
4. Grease building up. Kitchen lines that take a lot of fat build up faster than they wash through.
5. The clear didn’t finish the job. A rod or plunger can open a hole through a blockage without cleaning the pipe walls. Water runs again for a while, but most of the build-up is still there.

What actually tells you which it is

You can’t tell from above ground, and neither can a plumber without looking. A CCTV camera inspection shows the inside of the pipe: roots, cracks, displaced joints, dips, grease, and exactly where they sit and how deep. That’s the difference between clearing the same drain every few months and fixing it once.

A few things worth noting for whoever comes out:

• How often it blocks, and whether it’s worse in winter
• Which fixtures are affected first
• Whether there are big trees near the drain line, yours or a neighbour’s
• Any earlier camera reports or quotes — they’re useful

What not to do

• Don’t rely on chemical root killers or drain cleaners to fix a recurring blockage. They don’t fix a cracked or displaced pipe, and caustic products can damage the line and are a safety risk for whoever works on it next.
• Don’t open sewer inspection openings or the boundary trap while the line is blocked. They can hold sewage under pressure.
• Don’t ignore an overflowing gully between blockages. That’s the drain warning you it’s backing up.

Your options, from least invasive

A proper clean. Where the pipe is sound and the problem is build-up, the chain knocker and hydro jetter clean the pipe walls back to the pipe, not just a hole through the middle. For lines with a history, scheduled drain cleaning can keep them running.

Repair the damaged section. Where the camera shows cracks, displaced joints or roots getting in, the lasting fix is to deal with that section. Depending on the pipe, that’s relining it where suitable, or replacing it. For a line that has failed along its length, see drain and sewer renewals.

One fixed price, approved before any work starts. You see what we found on the screen, we talk you through the options and quote one fixed price for the one you choose. Nothing starts until you approve it. The quote is obligation-free.

The honest bit: on a pipe in poor condition, we’ll tell you that clearing it alone won’t hold, rather than come back and clear it again. Our workmanship is backed by a lifetime labour warranty. See real examples in our recent jobs.

Whose drain is it?

Everything on your side of the connection point is yours to maintain: the pipes under the house and yard, the overflow relief gully, and — in older suburbs — the boundary trap. Your water corporation (Yarra Valley Water, South East Water or Greater Western Water, depending on where you live) owns the sewer main itself, and the council owns the street's stormwater drains. Older and subdivided blocks sometimes share one combined drain across several properties, and a fault in the shared section is usually a shared cost. We camera and locate the fault first, so you know exactly whose side it sits on before anything is quoted — and if it turns out to be on the corporation's side, we'll say so and point you to their faults line rather than charge you for someone else's pipe. One tip worth acting on today: keep your overflow relief gully (the grated drain outside, usually near a side or rear wall) clear and uncovered. It's designed to spill outside instead of through your bathroom floor, and insurers can take a dim view of a blocked or built-over gully after a sewage spill.

Common questions

More plain-English help in our drain guides.