Blocked Drain at Night? What to Do in the First 30 Minutes

If a drain or toilet backs up at night, stop using water in the property, try a plunger on the affected sink or toilet, and check the outside gully or inspection chamber to see where the blockage is. Don’t mix drain chemicals or lift heavy covers on your own. If waste water is rising, coming up through a gully or entering the building, call a 24-hour drainage engineer.

First: stop adding water

Most out-of-hours call-outs get worse because someone keeps flushing to see if it has cleared. Every flush, shower or run of the washing machine adds more water to a pipe that can’t take it. Tell everyone in the house or building to stop using taps, toilets, showers and appliances until you know where the problem is.

If you live in a flat, let your neighbours know too. On a shared stack, water from upstairs can surface in the lowest flat or the basement.

Work out how big the problem is

Where the water backs up tells you a lot about where the blockage sits.

• One sink, bath or shower draining slowly: the blockage is probably in that fitting’s trap or waste pipe.
• One toilet filling up but everything else fine: likely in the WC pan or the short pipe behind it.
• Several fittings slow, or a toilet gurgling when the bath drains: the blockage is further down, in the main drain.
• Water rising in an outside gully or chamber, or coming up through a ground-floor fitting: the main drain or the sewer beyond it is blocked.

What’s safe to try

1. Use a plunger on a single blocked sink or toilet. For a sink, block the overflow with a damp cloth so the pressure goes down the pipe. For a toilet, use a flanged toilet plunger and work it firmly up and down a dozen times.
2. For a greasy kitchen or bathroom sink, pour a kettle of hot water that has cooled for a few minutes. Hot, not boiling: boiling water can crack ceramic and soften plastic waste pipes and joints.
3. Remove and clean the sink trap (the U-bend under the basin) if you’re comfortable doing it. Put a bucket underneath first, and expect it to be full.
4. Check the outside gully. Leaves, food scraps or a build-up of grease on the grid are common causes, and you can often clear them with gloves and a trowel.
5. Lift a light, plastic inspection chamber cover if you have one and can do it safely. If the chamber is empty, the blockage is upstream, between the house and the chamber. If it is full, the blockage is downstream.

What not to do

• Don’t mix drain chemicals, or pour one product after another. Some combinations react violently or give off harmful fumes, and the chemicals stay in the pipe for whoever clears it next.
• Don’t push a wire coat hanger into a toilet trap. It scratches the glaze, can get stuck, and rarely reaches the blockage.
• Don’t lift heavy cast-iron or concrete manhole covers on your own. They are heavy, they can trap fingers, and the open chamber is a fall hazard in the dark.
• Don’t keep flushing a toilet that is already near the rim.
• Don’t climb into or lean over a chamber. Sewer gases build up in confined spaces.

Keep yourself and the property safe

Treat any water that has come back up a drain as contaminated. Wear rubber gloves, keep children and pets away, and wash hands well. If water is near sockets, an extension lead or electrical fittings, switch off the power at the consumer unit if you can reach it safely, and stay out of standing water near live fittings.

Move anything valuable off the floor and put towels down at thresholds. Take a few photos of where the water has reached. If the property is insured, the photos will help later.

What happens when we arrive

We start by lifting the chambers to find the blockage and work out which way it is running. Most blockages clear with drain rods or high-pressure water jetting, which scours fat, scale and debris from the pipe wall rather than just punching a hole through. If a drain keeps blocking, or we suspect a broken or displaced pipe, we can put a CCTV camera down it to see what’s going on before any repair is discussed.

We give a free quotation before starting, and unblocking is usually done the same day.

Preventing the next one

• Only flush the three Ps: pee, poo and paper. Wet wipes, even ones labelled flushable, are a common cause of blocked drains.
• Wipe greasy pans with kitchen roll before washing up, and bin cooking fat once it has cooled.
• Fit a strainer in kitchen sinks and shower trays.
• Keep outside gullies clear of leaves, especially in autumn.

If your drain has backed up and the steps above haven’t cleared it, our drain unblocking team covers Central London 24 hours a day, 7 days a week. Call 020 3670 7648 and tell us what you can see. We’ll talk you through it and come out if it needs us.