Bathtub Drain Backing Up

A bath that fills with dirty water is a warning sign. Sometimes the cause is hair and soap in the trap. However, if the water smells of sewage, the problem is usually further down in the main drain.

Your toilet, sink, shower and bath all drain into one sewer line. Therefore a blockage in that shared pipe pushes water back up through the lowest fixture, which is often the bath. Plunging will not help here, since a plunger only works on a single fixture.

How to Tell if It Is the Main Sewer Line

Check for these signs, because they point to a blockage in the shared drain rather than in the bath itself. None of them needs any tools to spot:

• Bubbles appear in the toilet when you run the nearby sink, or the toilet water rises.
• You flush the toilet and water comes up in the bath or shower.
• The washing machine runs and the bath gurgles or fills.

Smell matters too, since the nose often spots the problem first. Dirty water that reeks of raw sewage almost always means a blocked main line. For a wider look at the causes, read about what causes a drain blockage.

Why Is Water Coming Up Through the Plughole?

You did not expect sewage in your bath, and nobody does. Still, the fault is rarely in the bath. Something blocks the pipes that carry waste away, further downstream.

Flushed items are a common cause. Wipes, nappies, sanitary products and cotton buds do not break down, because they hold together in water. Instead, they pile up in the pipe. Grease and tree roots can do the same. You can see more in our list of common causes of blocked drains.

If you think the main line is blocked, act at once, because a full blockage can push waste into the home, and the clean-up is unpleasant. Our guide on a sewer backup in the basement shows how bad this can get.

What to Do Next

First, stop using the water, because every flush or wash adds to the backlog. Then work out whether one fixture or several are affected.

If only the bath is slow, hair and soap are the likely cause. While you can lift out a little by hand with gloves, deeper blockages need more. For a blockage further down, read how to unblock a sewage drain and how to clear the main sewer line. For simple steps you can try at home, see what you can do to clear a blocked drain.

Sometimes the blockage sits outside the house. In that case, although the bath shows the symptom, a blocked drain outside the house may be the cause. Our team handles blocked baths and blocked drains of all kinds.

How to Stop It Happening Again

Fit a hair trap over the plughole. It is cheap, it catches most hair, and it is easy to empty. As a result, much less hair reaches the pipe. Rinse the trap after each shower, since a full trap blocks the flow itself.

Bin wipes, nappies, sanitary items and cotton buds instead of flushing them. Clear soap scum from the plughole now and then, because small build-ups grow. Our advice on how to keep your drain clear of blockage covers more habits worth adopting.

Watch for early signs too, because a blockage rarely arrives without warning. Slow draining and odd smells come first, and a blockage follows. Read how to know when your drain needs cleaning and how often drains should be cleaned to plan ahead.

Help Across North London

We cover drain unblocking in Enfield, blocked drains in Barnet and drain problems in Edgware. If the water still backs up after your own attempts, send the online enquiry form and we will arrange a visit.