How to unblock an outside drain — and when to stop

Lift the covers on every inspection chamber on the property, starting nearest the house and working towards the boundary. A chamber standing full of water is downstream of clear pipe; the first empty chamber past a full one tells you the blockage is in the run between them.

That five-minute check is exactly what a professional does first, and it saves you rodding the wrong pipe.

Use proper lifting keys, keep your back straight, and never put your fingers under the edge of a cast cover. Old covers seize — tap around the rim with a hammer to break the seal rather than yanking.

Wear waterproof gloves and wash thoroughly afterwards. Foul drain water carries E. coli, hepatitis A and leptospirosis. Keep children and pets away from an open chamber, and never leave one uncovered while you fetch a tool.

The gully — the grated pot at the bottom of a downpipe or outside the kitchen wall — is the easiest win. Lift the grate, put a gloved hand or a scoop in, and pull out the leaves, silt, wipes and grease.

Scrub the sides and flush it with a hose. If it drains away freely afterwards, that was your blockage. If it stands full, the pipe out of the gully is blocked.

Screw two rods together, feed them into the outlet of the full chamber, and add rods as you go. Always turn the rods clockwise as you push — the sections screw together clockwise, so turning the other way unscrews them and leaves rods stuck in your drain.

Push and pull in short strokes rather than driving hard at the obstruction. When it gives way, the water level in the chamber will drop suddenly. Flush plenty of clean water through afterwards, and hose and disinfect the rods before they go back in the shed.

Rods will move a soft blockage. They will not touch hardened fat, scale, root ingress, or a collapsed section — and pushing hard against a cracked pipe can turn a repairable defect into an excavation.

If the drain clears and then blocks again within weeks, the pipe has a defect. The only way to know is a CCTV survey; anything else is guessing.

A jetting unit runs a hose down the pipe and scours the full bore of it with water at up to 4,000 psi, cutting through fat, silt and fine roots and leaving the pipe at its original diameter — not just holed through.

It's the difference between the drain running again and the drain being clean. On a fat-heavy or root-affected drain, jetting plus a camera survey is the only thing that stops the repeat call-out.

Since 2011 most shared drains and the sewer beyond your boundary belong to the water company, and they will clear them at no cost to you. The pipework serving only your property is yours.

It's worth knowing before you pay anyone. Our drain responsibility checker walks you through it in about thirty seconds, and if the blockage is the water company's we'll tell you rather than sell you a job.

DrainFixer is a small family-run firm covering East Grinstead and 20 miles around, 24 hours a day, with jetters and cameras on every van.

Call 0330 1331 347 and you'll speak to someone, not a call centre.