Blocked Drain? What Works, What Makes It Worse

Start at the right end

One slow fixture is a local blockage, trap and waste arm, usually clearable yourself. Several fixtures backing up together, or water rising in an outside gully, means the shared run is blocked and home methods are done: that's rods or jetting.

What actually works

A plunger with the overflow blocked off. A drain snake through the trap. Enzyme cleaners overnight for grease. Pulling the trap off under a sink and emptying it, undignified, free, effective.

What makes it worse

Caustic soda poured into standing water creates a hot caustic pond an engineer then has to work through, most drain firms charge extra once chemicals are involved. And rodding blind into a clay run can punch through a weakened joint, turning a £150 clear into a £2,000 repair. If rods meet a hard stop, that's a survey, not more force.

Whose drain is it?

Since 2011, shared drains beyond your boundary generally belong to the water company, which means their problem, their bill. Before paying anyone to clear a shared run, check whether the blockage sits past the point where your neighbour's waste joins.

Rods: how to use them without doing damage

Always turn clockwise as you push, because rods unscrew anticlockwise and a section left underground is a considerably worse problem than the blockage. Push and withdraw repeatedly rather than forcing steadily. And stop if you meet something solid that will not move, in old clay drainage, force is what turns a blockage into a collapse.

What jetting does that rodding cannot

Rods punch a channel through a blockage; water scours the pipe wall. That difference is why a rodded fat-lined drain reblocks within months and a jetted one does not. On a run with a recurring problem, jetting plus a camera is usually cheaper over two years than three rodding visits.

Preventing the next one

Fat into a jar, not the sink. Strainers on plugholes. Nothing but paper down the toilet, including wipes marked flushable. And a kettle of hot water with washing-up liquid down the kitchen sink weekly. Deeply unexciting, and it prevents the large majority of the domestic blockages we attend.