Storm overflow register · Anglian Water

Willingham sewage works: storm overflow spills 2025

Willingham sewage treatment works, run by Anglian Water, has 1 monitored storm overflow discharging to River Till River Witham Nt. In 2025 it recorded 59 spills totalling 288 hours, against 54 spills and 292 hours in 2024. By hours spilling, it ranks 75 of 419 Anglian Water works, where 1 spilled longest.

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.

JanFebMarAprMayJunJulAugSepOctNovDecWillingham(Lincs) STW16 spills, 5.5 h, 1 Jan to 1 Jan67 spills, 55.2 h, 3 Jan to 8 Jan29 spills, 2.6 h, 9 Jan to 9 Jan46 spills, 7.5 h, 11 Jan to 14 Jan51 spills, 4.8 h, 24 Jan to 24 Jan151 spills, 17.1 h, 27 Jan to 28 Jan37 spills, 2 h, 30 Jan to 30 Jan41 spills, 4.9 h, 7 Feb to 8 Feb11 Feb 2025 12:34 GMT, 2 min6 spills, 1.1 h, 6 Jul to 6 Jul11 spills, 1 h, 8 Jul to 8 Jul5 spills, 2.8 h, 19 Jul to 19 Jul5 spills, 1.3 h, 20 Jul to 20 Jul39 spills, 2.9 h, 23 Jul to 25 Jul2 spills, 2.1 h, 3 Sep to 3 Sep3 spills, 1.4 h, 4 Sep to 4 Sep8 spills, 1.3 h, 17 Sep to 17 Sep22 spills, 5 h, 20 Sep to 21 Sep39 spills, 7.8 h, 23 Oct to 23 Oct4 spills, 0.3 h, 4 Nov to 4 Nov29 spills, 7.2 h, 10 Nov to 10 Nov7 spills, 0.8 h, 12 Nov to 12 Nov150 spills, 43 h, 14 Nov to 16 Nov73 spills, 7.7 h, 19 Nov to 19 Nov6 spills, 0.4 h, 23 Nov to 23 Nov176 spills, 28.4 h, 29 Nov to 1 Dec242 spills, 26.8 h, 4 Dec to 6 Dec84 spills, 9.9 h, 9 Dec to 9 Dec244 spills, 37.2 h, 16 Dec to 20 Dec

Hours spilling by month, 2025

0255075100Jan 2025: 95 hours spillingJanFeb 2025: 4.9 hours spillingFebMar 2025: 0.0 hours spillingMarApr 2025: 0.0 hours spillingAprMay 2025: 0.0 hours spillingMayJun 2025: 0.0 hours spillingJunJul 2025: 9.2 hours spillingJulAug 2025: 0.0 hours spillingAugSep 2025: 9.8 hours spillingSepOct 2025: 7.8 hours spillingOctNov 2025: 87 hours spillingNovDec 2025: 75 hours spillingDec
Hours, measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDuration
6 Jan 2025, 00:00Willingham(Lincs) STW1.0 days
14 Nov 2025, 07:00Willingham(Lincs) STW17.0 h
15 Nov 2025, 00:00Willingham(Lincs) STW10.8 h
18 Dec 2025, 13:48Willingham(Lincs) STW10.2 h
5 Jan 2025, 16:24Willingham(Lincs) STW7.6 h

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.

This works serves fewer than 2,000 people, or was not matched to a UWWTD report, so its size is not published. The population equivalent above is a placeholder of 1,000. Enter the population served if you know it.

Volume, central estimate4,940 m³range 1,968 - 12,402 m³
In litres4.9 millionrange 2.0 million - 12.4 million L
Olympic swimming pools2.0at 2,500 m³ each
Organic load, as people's raw sewage7,410person-days of untreated BOD

Assumed spill rate while spilling: 1.9 - 11.9 L/s (central 4.8 L/s), from a dry-weather flow of 1.9 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 79 kg445 kg2,480 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 207 kg2,099 kg8,942 kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 3.7 kg31 kg115 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 2.4 kg13 kg67 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 196.8 billion organisms4.9 trillion organisms124.0 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.

Willingham(Lincs) STW

Storm tank at sewage works · discharges to River Till River Witham Nt

Spills 2025
59 (288 hours) · up 9% on 2024
Spills 2024
54 (292 hours)
Long-term average
65.5 spills a year (monitored since 2022)
Monitor uptime
100% of the year
High-spill reason (company)
Performance - Asset configuration (e.g. PS/rising main/storm tanks)
Investigation
Env Act (SODRP) investigation ongoing, Operational investigation completed
Improvement
UWWTR improvement ongoing, Operational improvement ongoing
WFD catchment
Till (Witham) (GB105030062500)
Outlet location
SK8795084490 (OS grid reference) · View on Apple Maps
EA ID / permit
AWS01504 · ANNNF1407 · company name: WILLINGHAM 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.