A sink that takes its time to empty is easy to ignore, until it stops draining altogether. The good news is that most slow sinks have a simple cause close to the plughole. The trick is knowing when it's something further down the line.
Start with which sink it is
Kitchen sinks: grease and food
Fat, oil and food scraps are the main cause. Hot grease goes down as a liquid, then cools and sticks to the inside of the pipe. Over time it builds up, traps food and coffee grounds, and narrows the pipe until water barely gets through.
Bathroom basins: hair and soap
Hair wraps around the pop-up plug and combines with soap and toothpaste into a stubborn clump. This is usually within the first few centimetres of the drain.
Laundry tubs: lint and sand
Lint is the usual culprit. In coastal suburbs like Halls Head, Falcon, Dawesville and Silver Sands, sand from beach towels and wetsuits rinsed in the trough settles in the trap and the pipe below it.
What to try first
- Pull out the plug or strainer and clear any hair or debris you can see
- Use a sink plunger, with the overflow hole covered by a wet cloth
- Put a bucket underneath, unscrew the trap and clean it out
- Fit a drain strainer so it doesn't happen again
Skip the chemical drain cleaners. They can damage older pipes and fittings, they're unpleasant to handle if they don't work, and they're bad news on properties with a septic tank or aerobic treatment unit (ATU), where they can kill the bacteria the system needs.
Signs it's not just the sink
If the quick fixes don't help, the problem is probably further along. Watch for:
More than one fixture is slow
If the sink, shower and toilet are all sluggish, the blockage is usually in a shared drain or the main sewer line, not the sink itself.
Gurgling
Gurgling when another fixture drains, or when the toilet flushes, can mean a partial blockage or a problem with the drain's venting.
Water at the overflow gully
Most WA homes have an overflow relief gully outside, a grated drain with a loose cap. If water is coming up there, or the cap has lifted, the sewer line is blocked downstream. Stop using water and call a plumber.
Tree roots
In established suburbs like Halls Head, Dudley Park and older parts of central Mandurah, tree roots can get into clay sewer pipes through the joints. A slow sink that keeps coming back after it's cleared is a common sign.
Septic or ATU problems
On semi-rural blocks around Karnup, Pinjarra, Nambeelup and the Yunderups, slow drains throughout the house can mean the septic system itself needs attention, not the pipes.
How a plumber fixes it
For a blockage beyond the trap, a plumber can use a drain machine or high-pressure jetting to clear the line, and a camera to see what caused it. That tells you whether it was a one-off build-up or a damaged pipe that needs repair. See our blocked drains page for more.
Keeping sinks flowing
- Wipe greasy pans with paper towel before washing them
- Scrape food scraps into the bin, not the sink
- Use strainers in kitchen, basin and laundry drains
- Shake sand off beach gear outside before washing it
Sink still slow after you've tried the basics? Call Drainpro Plumbers on 0413 904 259. We clear drains across Mandurah and the Peel region, 24/7.