How often should you clear slow drains?

Slow drains become full blockages and backups if ignored.

A fully blocked drain backs up into the fixture and, in a shared stack, potentially into a lower one. Fats, oils and grease cool, harden and stick to the inside of pipes, and once set in a horizontal run they are difficult to remove.

1. Clear the visible debris first. Lift out the stopper or strainer and remove the hair and soap film that has collected on it. This alone fixes many slow drains.
2. Try a drain snake or hair removal tool. A cheap plastic barbed strip pulls out the hair mat sitting just below the plughole in a bathroom drain.
3. Flush with hot water. Run the hot tap for several minutes once the debris is out.
4. Use bicarbonate and vinegar for freshening. A few spoonfuls of bicarbonate followed by vinegar, left to fizz and then flushed through. This freshens a drain; it does not cure a real blockage.
5. Plunge properly if it is slow. Block the overflow with a wet cloth first, or the plunger just pushes air around. Use a cup plunger on sinks.
6. Clean the trap if that fails. Bucket underneath, unscrew the two collars on the U-bend, clear it, and refit. Most plastic traps undo by hand. In Australia, check your state’s licensing rules before dismantling any pipework.

• Water pooling around your feet in the shower
• A sink taking noticeably longer to empty than it used to
• Gurgling from another fixture when one drains
• A persistent smell from the drain
• Repeated blockages in the same fixture, which suggests a problem in the pipework rather than at the plughole

• Reaching for chemical drain opener first: it is hazardous if it fails and sits in standing water, and the US EPA’s septic guidance says to avoid it and use a drain snake instead
• Pouring fat and cooking oil down the sink, where it cools, hardens and sticks to the pipe
• Plunging without blocking the overflow, so the pressure escapes
• Using a plunger after adding chemical cleaner, which can splash caustic liquid

• Long-haired households need bathroom drains cleared far more often
• Kitchen sinks in households that cook with a lot of fat need more attention
• Tree roots grow into small cracks in external drains and cause recurring blockages that no amount of plunging fixes

Recurring blockages in the same place, multiple fixtures backing up at once, or any sewage smell or backup outside all indicate a problem in the main drain rather than the fixture. That needs a drainage specialist, often with a camera survey.