Storm Overflow Check by Postcode: Sewage Spills Near You

Enter a postcode and this check finds the monitored storm overflows within 1 km of the postcode point and shows, for the nearest, how many times it spilled and for how many hours in 2023, 2024 and 2025, with the monitor's uptime and the watercourse it discharges to. The figures are the water companies' annual returns to the Environment Agency. England only, not live status.

No signup. Postcode-point screen of the Environment Agency's storm-overflow annual returns (Event Duration Monitoring, England), published under the Open Government Licence v3.0.

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What this check reads

The Environment Agency dataset Event Duration Monitoring: Storm Overflows, Annual Returns, published under the Open Government Licence. Each year's file lists every monitored storm overflow in England with the site name on its permit, the permit reference, the asset type, the outlet's grid reference, the receiving water, the counted spills (using the 12–24 hour counting method), the total duration of all spills, the long-term average and the percentage of the year the monitor was operating. This check holds the 2023, 2024 and 2025 returns and finds the overflows within 1 km of the postcode point, nearest first.

How to read spill counts and hours

What you seeHow to read it
SpillsDischarge events counted by the 12–24 hour method: a first 12 hours of discharge counts as one spill, each following 24-hour block as another. A single long wet-weather discharge can therefore count as several.
HoursThe total time the overflow was discharging in the year, before the counting method is applied. Hours tell you more about how much went into the watercourse than the spill count does.
Monitor uptimeThe share of the year the monitor was recording. Anything well under 90% means the year is understated, and the companies must explain why in the return.

What matters to a buyer

Three practical questions. Flooding: a watercourse that receives storm sewage carries foul water when it floods, so an overflow upstream of a home with flood history changes what a flood means; read the flood-risk check for the same postcode. Amenity and odour: an outfall that spilled for hundreds of hours a year into a beck at the end of the garden is a different proposition from one that spilled twice. Bathing and shellfish waters: where the result names a designated bathing water, the overflow is one the Environment Agency monitors for that reason, and the water's classification is published separately.

What this check does not cover

It is not live status: the companies' own maps show whether an overflow is discharging now. It does not include overflows that were not yet monitored in the years held, nor private or unpermitted discharges. It covers England only. A storm overflow is permitted sewer infrastructure, not a record of contamination on the plot; nothing here is a finding about the ground under a property.

What the report adds

The Lite and Complete reports print a Storm overflows near this address block inside the contaminated-land and environmental-permits section: every monitored overflow within 1 km with its spill count and total hours for each year the return covers, flagged where the monitor ran under 90 % of the year, the watercourse it discharges to, and, where the permit reference aligns, the same overflow matched to its entry on the public discharge register, so the permit and the spill record sit side by side. The flood section of the same report carries the mapped zone, the surface-water band now and in the 2050s, recorded flood extents and the defences nearby with their recorded condition. Read what an environmental search covers, or check the flood history for the postcode.

Frequently asked questions

What is a storm overflow, and is it the same as a combined sewer overflow (CSO)?
Yes, in everyday use. A storm overflow is a permitted release point on a combined sewer (one carrying both rainwater and sewage) that discharges diluted, screened sewage to a river, beck or the sea when heavy rain would otherwise back the network up into streets and homes. Overflows on the sewer network, inlet and storm-tank overflows at treatment works and storm discharges at pumping stations are the asset types; all are reported in the Environment Agency's annual return.
Does a storm overflow near a house mean sewage on the property?
No. The overflow discharges to the receiving watercourse named in the result, not onto land. It is sewer infrastructure, not a contaminated-land record. Where overflows touch a home is through river flooding (floodwater from a watercourse that receives storm sewage is foul), odour on hot days near a frequently spilling outfall, and amenity: a river you would not want children paddling in. Check the flood history for the postcode alongside this result.
How many spills a year is a lot?
The Storm Overflows Discharge Reduction Plan for England sets a long-term target of no more than 10 spills a year on average per overflow by 2050, with high-priority sites first. The 2025 return still shows many overflows in the dozens and some in the hundreds. Compare the three years side by side, and read a low monitor-uptime year as understating the true count.
Why are the figures not live?
This check reads the regulatory annual return, which each water and sewerage company submits to the Environment Agency after the calendar year ends and which is published the following spring (the 2025 return was revised in August 2026). Live 'spilling now' feeds exist on the water companies' own maps; they answer a different question. A buyer wants the pattern over years, which is what the return gives.
What does monitor uptime mean and why does it matter?
Each overflow has an event duration monitor. The return reports the percentage of the year it was working. A monitor that ran for 6% of the year cannot have counted most of that year's spills, so the spill figure beside it understates reality. The check prints the uptime next to every year for that reason.
Does this cover Wales, Scotland and Northern Ireland?
No. This check reads the return for England only. The file also carries Dŵr Cymru Welsh Water's rows, but Welsh overflows are regulated by Natural Resources Wales and the check does not use them; Scottish Water's go to SEPA and Northern Ireland Water's to the Northern Ireland Environment Agency. A postcode outside England returns a 'not covered' answer rather than a false 'none found'.

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