A drain overflowing when it rains can leave you unsure whether to call a drainage company, your water company or the council. A blockage is one possible cause. However, heavy rain can also overwhelm a drainage system that has no blockage. The location of the water and the way it behaves can help you describe the problem.
First, keep away from floodwater and any lifted or damaged covers. If water threatens your home or there is sewage outside, seek help promptly. Avoid lifting inspection covers or running extra water to test a drain that is already overflowing.
Why is your drain overflowing when it rains?
Leaves and debris can restrict the route into a surface water drain. A blockage further along a pipe may also reduce how much water it can carry. As a result, water can back up during a downpour even if the drain seemed fine in dry weather.
However, rainfall alone can sometimes exceed a sewer’s capacity. Severn Trent explains the causes of sewer flooding, including blockages and unusually large volumes of rain. Clearing a private drain will only help if a restriction in that drain is part of the problem. An engineer needs to assess the symptoms before recommending work.
Safe checks for a drain overflowing when it rains
You can gather useful details from a safe, dry position. For example, note whether water collects beside a downpipe, comes up through a cover or flows onto your property from the road. You do not need to open the drainage system to record what you can see.
- Record the timing. Does the overflow start during light rain or only in a heavy downpour? Note whether water remains once the rain stops.
- Describe the location. Give the nearest door, downpipe, boundary or road landmark. Take photographs only if you can do so safely.
- Note other symptoms. Tell the person you contact if toilets or sinks are also backing up. Mention any similar flooding at neighbouring homes.
Also note whether anyone has recently cleared the drain and whether the same issue returned. These details help distinguish a recurring obstruction from a wider drainage problem.
Who should you contact about the overflow?
Who can help depends on the source. For a suspected blockage in a drain serving your own property, ask for advice about a private drain assessment. If several properties are affected or you suspect a public sewer, contact your wastewater company. Severn Trent’s sewer pipe responsibility guide explains the distinction between private drains, shared sewers and highway drainage.
For a blocked road gully, report the problem to the local highways authority. Surface water flooding may need the local council’s flood team. If the source is unclear, GOV.UK’s flood reporting guide helps you find the relevant organisation. Give them your observations and explain whether water is entering a building.
What if the overflow keeps coming back?
For a recurring private drain problem, keep a short record of each incident. Include the rainfall, the place where water appeared and any work already carried out. Then ask what checks would help establish the cause.
A CCTV drain survey may help inspect an accessible pipe for an obstruction or defect. Where a blockage is the cause, drain unblocking and cleaning may be appropriate. The findings should guide the next step.
If you have a private drain overflowing when it rains in Coventry or the surrounding area, contact Central Drains. Tell us where the water appears, when it started and whether other drains are affected. We can discuss the problem and advise on arranging an assessment.