Storm overflow register · United Utilities

Barton sewage works: storm overflow spills 2025

Barton sewage treatment works, run by United Utilities, has 1 monitored storm overflow discharging to Barton Brook. In 2025 it recorded 147 spills totalling 2,207 hours, against 170 spills and 2,640 hours in 2024. By hours spilling, it ranks 7 of 289 United Utilities works, where 1 spilled longest.

Works size: 7,154 population equivalent (BARTON 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.

JanFebMarAprMayJunJulAugSepOctNovDecBarton Waste Water…1 Jan 2025 00:00 GMT, 221.4 h4 spills, 67.8 h, 14 Jan to 17 Jan15 spills, 66.5 h, 20 Jan to 25 Jan14 spills, 39.1 h, 27 Jan to 28 Jan7 spills, 13.7 h, 19 Feb to 20 Feb15 spills, 22.1 h, 23 Feb to 25 Feb4 spills, 11.6 h, 26 Feb to 27 Feb23 Mar 2025 00:45 GMT, 22.9 h16 Apr 2025 21:12 GMT, 46 min1 May 2025 18:27 GMT, 3 h4 spills, 10.4 h, 24 May to 25 May6 spills, 28.3 h, 26 May to 28 May3 spills, 23.7 h, 29 May to 30 May10 spills, 17.2 h, 3 Jun to 4 Jun15 spills, 57.2 h, 5 Jun to 9 Jun11 spills, 28.8 h, 9 Jun to 11 Jun2 spills, 24.8 h, 14 Jun to 15 Jun4 spills, 6.3 h, 22 Jun to 23 Jun24 Jun 2025 08:30 GMT, 3.1 h2 spills, 5.5 h, 28 Jun to 29 Jun3 spills, 10.1 h, 4 Jul to 5 Jul3 spills, 4.5 h, 15 Jul to 15 Jul20 Jul 2025 18:40 GMT, 8.3 h3 Aug 2025 09:38 GMT, 2 h5 spills, 11.7 h, 4 Aug to 4 Aug2 spills, 9.6 h, 4 Sep to 4 Sep2 spills, 14 h, 7 Sep to 8 Sep21 spills, 167.8 h, 10 Sep to 19 Sep9 spills, 61.4 h, 20 Sep to 23 Sep27 Sep 2025 21:07 GMT, 5.6 h1 Oct 2025 06:18 GMT, 8.1 h4 spills, 76.4 h, 2 Oct to 6 Oct4 spills, 8.6 h, 19 Oct to 20 Oct5 spills, 32.1 h, 21 Oct to 23 Oct15 spills, 29 h, 24 Oct to 25 Oct40 spills, 276.5 h, 26 Oct to 8 Nov22 spills, 175.8 h, 9 Nov to 17 Nov7 spills, 39.6 h, 18 Nov to 20 Nov12 spills, 59.3 h, 22 Nov to 25 Nov4 spills, 4.4 h, 26 Nov to 26 Nov25 spills, 327 h, 28 Nov to 13 Dec22 spills, 201.8 h, 14 Dec to 23 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.

050k100k150k200kJan 2025: 395 h spilling ≈ 48,407 m³ (range 19,281-121,527 m³)JanFeb 2025: 47 h spilling ≈ 5,798 m³ (range 2,309-14,556 m³)FebMar 2025: 23 h spilling ≈ 2,807 m³ (range 1,118-7,047 m³)MarApr 2025: 0.8 h spilling ≈ 98 m³ (range 39-246 m³)AprMay 2025: 65 h spilling ≈ 8,017 m³ (range 3,193-20,126 m³)MayJun 2025: 143 h spilling ≈ 17,504 m³ (range 6,972-43,945 m³)JunJul 2025: 23 h spilling ≈ 2,807 m³ (range 1,118-7,047 m³)JulAug 2025: 14 h spilling ≈ 1,679 m³ (range 669-4,216 m³)AugSep 2025: 258 h spilling ≈ 31,675 m³ (range 12,617-79,520 m³)SepOct 2025: 269 h spilling ≈ 32,974 m³ (range 13,134-82,782 m³)OctNov 2025: 493 h spilling ≈ 60,371 m³ (range 24,047-151,563 m³)NovDec 2025: 477 h spilling ≈ 58,458 m³ (range 23,285-146,762 m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
1 Jan 2025, 00:00Barton Waste Water Treatment Works9.2 days10,809 - 68,129 m³
4 Dec 2025, 08:03Barton Waste Water Treatment Works7.8 days9,082 - 57,240 m³
9 Nov 2025, 14:15Barton Waste Water Treatment Works4.5 days5,276 - 33,251 m³
27 Oct 2025, 05:52Barton Waste Water Treatment Works3.7 days4,389 - 27,661 m³
17 Dec 2025, 07:24Barton Waste Water Treatment Works3.7 days4,367 - 27,522 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 estimate270,582 m³range 107,779 - 679,308 m³
In litres270.6 millionrange 107.8 million - 679.3 million L
Olympic swimming pools108at 2,500 m³ each
Organic load, as people's raw sewage405,874person-days of untreated BOD

Assumed spill rate while spilling: 13.6 - 85.5 L/s (central 34.0 L/s), from a dry-weather flow of 13.6 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 4,311 kg24,352 kg135,862 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 11,317 kg114,998 kg489,781 kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 205 kg1,705 kg6,318 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 129 kg704 kg3,668 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 10.8 trillion organisms270.6 trillion organisms6.8 × 10¹⁵ 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.

Barton Waste Water Treatment Works

Storm tank at sewage works · discharges to Barton Brook

Spills 2025
147 (2,207 hours) · down 14% on 2024
Spills 2024
170 (2,640 hours)
Long-term average
156.8 spills a year (monitored since 2021)
Monitor uptime
100% of the year
High-spill reason (company)
Not asset maintenance - Hydraulic capacity
Investigation
No investigation activity in reporting period
Improvement
No improvement action in reporting period
WFD catchment
Barton (Westfield) Brook (GB112072065800)
Outlet location
SD5147035720 (OS grid reference) · View on Apple Maps
EA ID / permit
UUP00200 · 017260043 · company name: BARTON WwTW

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 United Utilities 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.