Tips for cleaning your drains

Drains that block slowly were usually fouled slowly. A basin that takes a minute to empty has often been collecting soap scum, hair and cooking grease for months, and a hasty unblocking with a caustic product, a boiling kettle or a wire coat hanger can do more damage in one evening than the blockage did in a year. A gentler order of work, followed by a few daily habits, prevents most of the problem from developing in the first place.

Start with a plunger, used properly

A cup plunger over the waste, with enough water in the basin to cover the cup, and a wet cloth stuffed into the overflow hole. Without that cloth, the air simply escapes up the overflow and the plunger pumps nothing. Then firm, rhythmic strokes, ten to twenty, without breaking the seal. On a double-basin sink or a bath with a lever waste, block the second outlet the same way. A plunger moves the blockage mechanically, touches nothing else and costs nothing, so it is the sensible first move for soft blockages such as soap, hair and food.

The trap, in five minutes, with a bowl

Under every basin and bath lives a trap, the U or bottle bend holding a seal of water against drain smells. In a blocked basin, the trap is often where the block sits, which makes emptying it a high-yield DIY job. Put a bowl underneath, wear gloves, and unscrew the trap's compression nuts by hand (a strap wrench helps if they have been overtightened previously). Lift the trap out and empty it into the bowl. What comes out is often the whole story: a felted plug of hair and soap in the shower, or a layer of grease in the kitchen. Rinse the trap, check the washers are supple, reassemble hand-tight, run water, and check for weeps.

Assessing the common home remedies

Bicarbonate followed by vinegar, left to fizz and chased with hot water: harmless, mildly useful on smells and slow soap-scum drains, but of little use on a real blockage, because the fizz works in the basin rather than down the pipe where the block sits. Boiling water on a kitchen sink: effective on pure fat, but a risk on PVC pipe and on ceramic basins in cold weather, where thermal shock can crack things; hot tap water poured slowly achieves much of the benefit without that lottery. Caustic soda (sodium hydroxide): it works and generates heat in the pipe, but it will burn skin and eyes, it attacks old jointing compound and some plastics, and mixing it with a plunger afterwards throws it back at you. A sensible order is plunger first, then trap, then a drainage professional if neither clears it. Keep the caustic bottle as a last resort, wear goggles, never mix it with other chemicals, and never use it in a drain already dosed with something else.

The kitchen: grease is the main enemy

Fats, oils and grease, cooling fat from pans, roasting tins and the fryer, set in the pipe and catch everything that follows. Bin it, don't block it is the rule to follow. Fat goes into a tin or tub then the bin, the pan is wiped with kitchen paper before it meets the wash-up water, and a strainer sits over the sink waste every day. A weekly flush of the kitchen run with hot soapy water, detergent and the hottest tap water, a full basin released at once, helps keep the last of the grease moving. These four habits prevent most kitchen drain problems.

The bathroom: catch hair early

A hair catcher over the shower waste is a high-return object in a bathroom. Clean it weekly, before it becomes a wig. Basin pop-up wastes collect the same felt in smaller quantities; emptying the trap catches the rest. Toothpaste and soap scum respond to the hot-flush habit; dental floss belongs nowhere near a drain, because it knits blocks together.

When to stop and call for help

Water coming back up a drain that is not the one you are using; a smell of drains in the house that emptying traps does not shift; the outside inspection chamber standing full when the kitchen sink runs; or every outlet on one floor slow at once. Those are the signatures of a blockage beyond the trap, in the run under the floor or out to the sewer, and they call for rods and possibly a camera rather than a bottle. At that point a qualified drainage professional is needed.

What this sheet does not cover

Septic tanks and private drainage, communal stacks in flats (a managing agent matter), and the drain-locator and CCTV work that a recurring blockage eventually deserves are outside the scope of this sheet. If yours is a garden gully flooding outside, the first question is whose side of the boundary it sits on, and that question is better answered with a plan and a torch than with a bottle of anything.