Can blocked drains cause subsidence?

January 26, 2021

Subsidence is a very serious problem which can be costly and expensive for any home or property owner.

Subsidence occurs when your home starts to sink into the ground beneath and can occur when the ground either shrinks back or swells due to local weather conditions. Particularly if there has been periods of heavy rain after hot weather.

Subsidence is far more likely to occur when a house has been built on a clay foundation but houses built on any kind of soil under your home can also start to sink.

Unfortunately in England and Wales, subsidence is a common problem. In fact many of the major towns and cities in the West Midlands, including Birmingham, Wolverhampton, Stoke on Trent and Lichfield are all susceptible, as well as other major cities in the UK such as London and Manchester.

Reasons for this are in part due to the soil type, but also due to the increased weight and pressure on the ground due to lots of buildings and skyscrapers in a relatively condensed area. Also ground water in the area is often used up, which can cause soil to dry out and compact.

If you want to find out how much risk your area has then check out which has handy UK regional maps to show areas most at risk.

What are the causes of subsidence in the home?

A very common cause of subsidence can be blocked drains. When you have drainage problems, the drains and pipes can’t do their job of removing wastewater from the property effectively. Obviously this water needs to go somewhere and quite often can form puddles on your property or seep into the soil under your home, washing it away to make it less stable.

Water in the drains can also attract tree roots to the pipe, causing tree root ingress which can compound the problem by causing leaking drains, or even collapsed drains. Not only that as the tree grows so do the roots, which can cause the ground to get more unstable.

In every case it is important to spot signs of blocked drains as soon as possible before subsidence can occur.

The signs of blocked drains

Fortunately, the signs of blocked drains can be very easy to spot.

  • Bad smells – A blocked drain stinks. If you notice any unpleasant odour from your drains, or a sink or tap then you may need to investigate further.
  • Sluggish drainage – If water drains more slowly, then it could be a blocked drain causing water to filter down slowly.
  • Higher water levels – often a blocked drain will cause water to go back up the drainage system as it looks for somewhere to go, so if you flush the toilet and the water rises higher than usual then it could indicate a drainage issue.


  • Gurgling noises – Gurgling sounds coming from a drain will indicate a blocked drain as it suggests air has found its way into the drain from a blockage.

Avoiding blocked drains

Of course, prevention is better than cure when it comes to blocked drains. Check out our blog on the top 10 things to avoid flushing down there.

You can also use things like a sink strainer or a fat catch trapper to prevent things like grease and food going down the drains.

Signs of subsidence

Subsidence can usually be prevented if possible causes are acted upon quickly but here are the tell tale signs:

  • Cracks in ceilings, walls and outdoor brickwork.
  • Existing cracks spreading and getting wider.
  • Cracks showing up after a long dry spell of weather
  • Wallpaper rippling when no damp is present.
  • Doors and windows have started to stick.

If you notice any of these issues and your home has started to suffer from subsidence then you need to take immediate advice to get a handle on the problem as the sooner it is looked at the quicker and cheaper it is to fix

You may need to speak to your home insurance provider to cover costs, though usually policies only cover subsidence damage if subsidence has never occurred although if the property has a history of subsidence you may require specialist insurance and also may need to pay a large excess due to the costs involved in repairing damage caused by subsidence. Therefore it is even more important to spot any possible causes of subsidence and rectify them immediately

If you spot any of the signs of blocked drains, then it is important to act quickly. Call Argo Drains on 0121 663 6683 – we conduct emergency drain unblocking and drain repairs throughout the West Midlands.

If you are unsure if a drain is blocked, you can also contact us about a CCTV drain survey to identify and diagnose any drainage problems.