Storm overflow register · Anglian Water

Donington sewage works: storm overflow spills 2025

Donington sewage treatment works, run by Anglian Water, has 1 monitored storm overflow discharging to Mill Drain. In 2025 it recorded 45 spills totalling 212 hours, against 111 spills and 692 hours in 2024. By hours spilling, it ranks 104 of 419 Anglian Water works, where 1 spilled longest.

Works size: 2,616 population equivalent (DONINGTON STW, UWWTD 2018). Used for the spill volume estimate.

Every spill in 2025

Each blue mark is one spill, placed by when it started and sized by how long it lasted. Hover over a mark for the date and duration.

JanFebMarAprMayJunJulAugSepOctNovDecDonington Water…198 spills, 66.1 h, 5 Jan to 10 Jan2 spills, 0.2 h, 27 Jan to 27 Jan58 spills, 5.5 h, 8 Feb to 9 Feb51 spills, 3.7 h, 10 Feb to 12 Feb3 spills, 0.3 h, 26 Feb to 26 Feb13 spills, 2.1 h, 15 Apr to 15 Apr3 spills, 2.3 h, 24 Apr to 24 Apr4 spills, 4.1 h, 28 May to 28 May4 spills, 1.3 h, 14 Sep to 14 Sep13 spills, 2.9 h, 17 Sep to 17 Sep2 spills, 0.3 h, 3 Oct to 3 Oct6 spills, 2.8 h, 23 Oct to 23 Oct9 spills, 4.1 h, 1 Nov to 1 Nov3 spills, 0.4 h, 10 Nov to 10 Nov28 spills, 6.5 h, 12 Nov to 12 Nov90 spills, 43.1 h, 14 Nov to 16 Nov2 spills, 0.2 h, 19 Nov to 19 Nov33 spills, 4.2 h, 23 Nov to 23 Nov9 spills, 1.3 h, 29 Nov to 29 Nov10 spills, 1.8 h, 1 Dec to 2 Dec118 spills, 26.7 h, 4 Dec to 7 Dec30 spills, 6 h, 9 Dec to 10 Dec25 spills, 4.5 h, 16 Dec to 16 Dec67 spills, 20.8 h, 18 Dec to 19 Dec3 spills, 0.2 h, 21 Dec to 22 Dec

Estimated spill volume by month, 2025

Hours spilling each month × the estimated spill rate for a works of this size. The bars are central estimates and the whiskers show the low-high range. Method.

02,0004,0006,0008,000Jan 2025: 66 h spilling ≈ 2,972 m³ (range 1,184-7,461 m³)JanFeb 2025: 9.5 h spilling ≈ 426 m³ (range 170-1,069 m³)FebMar 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)MarApr 2025: 4.5 h spilling ≈ 202 m³ (range 80-506 m³)AprMay 2025: 4.1 h spilling ≈ 184 m³ (range 73-461 m³)MayJun 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)JunJul 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)JulAug 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AugSep 2025: 4.2 h spilling ≈ 188 m³ (range 75-473 m³)SepOct 2025: 3.1 h spilling ≈ 139 m³ (range 55-349 m³)OctNov 2025: 60 h spilling ≈ 2,680 m³ (range 1,068-6,729 m³)NovDec 2025: 60 h spilling ≈ 2,689 m³ (range 1,071-6,752 m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
6 Jan 2025, 03:50Donington Water Recycling Centre20.2 h360 - 2,269 m³
14 Nov 2025, 07:58Donington Water Recycling Centre16.0 h286 - 1,804 m³
15 Nov 2025, 00:00Donington Water Recycling Centre10.2 h182 - 1,148 m³
18 Dec 2025, 14:22Donington Water Recycling Centre7.8 h139 - 874 m³
7 Jan 2025, 00:00Donington Water Recycling Centre6.2 h110 - 694 m³

Estimated 2025 spill volume and pollution

Estimate, not a measurement. Monitors record how long an overflow spills, not how much. This calculator back-calculates a spill rate from the size of the works, using the Environment Agency's permit formulae, and multiplies it by published storm-sewage concentrations. How it works.

Volume, central estimate9,485 m³range 3,778 - 23,812 m³
In litres9.5 millionrange 3.8 million - 23.8 million L
Olympic swimming pools3.8at 2,500 m³ each
Organic load, as people's raw sewage14,227person-days of untreated BOD

Assumed spill rate while spilling: 5.0 - 31.3 L/s (central 12.5 L/s), from a dry-weather flow of 5.0 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 151 kg854 kg4,762 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 397 kg4,031 kg17,168 kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 7.2 kg60 kg221 kg 1.9 / 6.3 / 9.3 mg/L
Low: Germany, Brombach 2005; typical/high: Paris range 3.3-9.3 midpoint and top, Gasperi 2012 (via botturi); no UK value found
Total phosphorus 4.5 kg25 kg129 kg 1.2 / 2.6 / 5.4 mg/L
Low/high: Paris, Gasperi 2012; typical: Slovakia (via botturi). UK figure of 10 mg/L treated as an outlier
E. coli 377.8 billion organisms9.5 trillion organisms238.1 trillion organisms 10,000 / 100,000 / 1.0 million per 100 mL
Median range at CSO and retention-tank outlets, Stott et al. 2018 (via botturi); typical = log midpoint

Low combines the low spill rate with low concentrations, and high combines high with high, so the true figure is very likely inside the range. Long spills become more diluted as they go on, so the central figure tends to overstate the load of long events. The calculator does not estimate the effect on the receiving water, which depends on river flow or tide at the time of the spill.

Donington Water Recycling Centre

Storm tank at sewage works · discharges to Mill Drain

Spills 2025
45 (212 hours) · down 59% on 2024
Spills 2024
111 (692 hours)
Long-term average
84.5 spills a year (monitored since 2022)
Monitor uptime
100% of the year
High-spill reason (company)
Not Applicable - Ongoing investigation
Investigation
Env Act (SODRP) investigation ongoing, Operational investigation completed
Improvement
No improvement action in reporting period
WFD catchment
Black Sluice IDB draining to the South Forty Foot Drain (GB205030051515)
Outlet location
TF1960034870 (OS grid reference) · View on Apple Maps
EA ID / permit
AWS00345 · AW5NF812 · company name: DONINGTON STW

How the estimate works

  1. Dry-weather flow (DWF) = population × water use per person × (1 + infiltration). Water use is 136.5 L per person per day, England's per-capita consumption for 2024-25 [EA]. Infiltration of groundwater into sewers is taken as 0-40% of that flow [Escritt, via HBF]. The Environment Agency defines DWF as PG + I + E [EA].
  2. Population. The size of each works comes from the load entering it as reported under the Urban Waste Water Treatment Directive, in population equivalents (1 p.e. = 60 g of BOD a day) [UWWTD]. We treat population equivalent as population. That overstates flow where trade effluent adds load, and no official source links the two. Works serving fewer than 2,000 p.e. are not reported, so their size has to be entered by hand.
  3. Low spill rate = DWF. This is the method used by Giakoumis & Voulvoulis (2026), which they note likely underestimates storm loads [G&V].
  4. High spill rate = Formula A − flow to full treatment = (DWF + 1360P) − 3DWF. This is the largest flow the permit expects the storm tanks to handle before it passes on to treatment or overflows [EA]. The central rate is the geometric mean of the low and high rates.
  5. Volume = spill rate × hours spilling, with hours taken from the event duration monitor.
  6. Pollution = volume × published storm-sewage concentrations [Botturi et al.] [US EPA]. Organic load is also shown as person-days of untreated sewage at 60 g of BOD per person per day [UWWTD].

What this cannot tell you. It gives no real flow for any single spill, and no effect on the river or sea, which depends on the flow, tide and the other pressures on the water at the time. It gives no figure for spills from overflows on the sewer network, which serve catchments of unknown size. It is a way to put hours into rough physical terms, not a substitute for flow monitoring.

Sources

  1. EA: Water companies - environmental permits for storm overflows and emergency overflows
  2. EA: Water resources 2024 to 2025 - per capita consumption
  3. HBF: Foul sewer design - historic conventions (citing Escritt 1984 on infiltration)
  4. Giakoumis & Voulvoulis (2026), Environ. Sci.: Water Res. Technol., doi:10.1039/D5EW00860C
  5. Botturi et al. (2021), Crit. Rev. Environ. Sci. Technol. 51:1585 - CSO quality review, Table 2
  6. US EPA (2004) Report to Congress on CSOs and SSOs, chapter 4
  7. Urban Waste Water Treatment Directive, Article 2(6): 1 p.e. = 60 g BOD5/day
  8. Olympic-size swimming pool: 2,500 m³ at the nominal 2 m depth

← All Anglian Water works · Contains Environment Agency data licensed under the Open Government Licence v3.0. Spill start and stop times: © Environment Agency copyright and/or database right 2026. All rights reserved. They are water-company data and have not been verified by the Environment Agency. Works size: EEA Waterbase UWWTD. How to read the data.