Storm overflow register · United Utilities

Barrow In Furness sewage works: storm overflow spills 2025

Barrow In Furness sewage treatment works, run by United Utilities, has 2 monitored storm overflows discharging to Walney Channel (estuarine waters). In 2025 they recorded 113 spills totalling 1,202 hours, against 154 spills and 1,444 hours in 2024. By hours spilling, it ranks 36 of 289 United Utilities works, where 1 spilled longest.

Works size: 70,563 population equivalent (BARROW-IN-FURNESS 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.

JanFebMarAprMayJunJulAugSepOctNovDecBarrow-in-Furness WwTW6 spills, 36.4 h, 1 Jan to 2 Jan5 spills, 3.3 h, 3 Jan to 4 Jan5 spills, 64.6 h, 5 Jan to 8 Jan11 spills, 8.8 h, 24 Jan to 24 Jan10 spills, 14.5 h, 27 Jan to 28 Jan3 spills, 23.2 h, 14 Jun to 15 Jun15 Jul 2025 15:45 GMT, 7.4 h6 spills, 37.5 h, 15 Sep to 17 Sep2 spills, 56.1 h, 19 Sep to 22 Sep20 spills, 56.9 h, 3 Oct to 5 Oct4 spills, 72.9 h, 3 Nov to 6 Nov25 spills, 90.6 h, 10 Nov to 15 Nov3 spills, 10.1 h, 18 Nov to 19 Nov9 spills, 21.5 h, 22 Nov to 23 Nov2 spills, 28.6 h, 27 Nov to 28 Nov48 spills, 210.8 h, 1 Dec to 12 Dec70 spills, 155.8 h, 14 Dec to 22 DecBarrow-in-Furness WwTW12 spills, 13.2 h, 1 Jan to 1 Jan15 spills, 27.6 h, 5 Jan to 7 Jan5 spills, 3.6 h, 24 Jan to 24 Jan3 spills, 1 h, 27 Jan to 27 Jan11 spills, 10.7 h, 14 Jun to 14 Jun11 spills, 1.6 h, 15 Jul to 15 Jul4 Aug 2025 08:13 GMT, 2 min25 spills, 8.4 h, 15 Sep to 16 Sep5 spills, 9.3 h, 17 Sep to 17 Sep27 spills, 28.5 h, 19 Sep to 21 Sep9 spills, 13.2 h, 3 Oct to 5 Oct74 spills, 28.7 h, 3 Nov to 5 Nov19 spills, 6.7 h, 10 Nov to 11 Nov14 spills, 8.2 h, 12 Nov to 13 Nov10 spills, 4.7 h, 14 Nov to 15 Nov7 spills, 3.4 h, 18 Nov to 18 Nov19 spills, 4.5 h, 23 Nov to 23 Nov7 spills, 3.3 h, 27 Nov to 27 Nov4 spills, 0.7 h, 28 Nov to 28 Nov28 spills, 25.9 h, 1 Dec to 2 Dec14 spills, 4 h, 4 Dec to 4 Dec53 spills, 54 h, 5 Dec to 9 Dec35 spills, 17.9 h, 14 Dec to 15 Dec28 spills, 20.2 h, 17 Dec to 19 Dec12 spills, 3.8 h, 22 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.

0500k1M1.5MJan 2025: 173 h spilling ≈ 209,046 m³ (range 83,267-524,818 m³)JanFeb 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)FebMar 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)MarApr 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AprMay 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)MayJun 2025: 34 h spilling ≈ 40,987 m³ (range 16,326-102,900 m³)JunJul 2025: 8.9 h spilling ≈ 10,761 m³ (range 4,286-27,015 m³)JulAug 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AugSep 2025: 140 h spilling ≈ 169,026 m³ (range 67,327-424,347 m³)SepOct 2025: 70 h spilling ≈ 84,755 m³ (range 33,760-212,780 m³)OctNov 2025: 284 h spilling ≈ 343,009 m³ (range 136,628-861,139 m³)NovDec 2025: 492 h spilling ≈ 595,340 m³ (range 237,136-1.5 million m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
5 Dec 2025, 16:10Barrow-in-Furness WwTW5.1 days58,810 - 370,671 m³
3 Nov 2025, 01:46Barrow-in-Furness WwTW3.0 days34,747 - 219,003 m³
5 Jan 2025, 08:15Barrow-in-Furness WwTW2.7 days30,645 - 193,152 m³
19 Sep 2025, 20:00Barrow-in-Furness WwTW2.3 days27,009 - 170,235 m³
17 Dec 2025, 13:50Barrow-in-Furness WwTW2.1 days23,710 - 149,442 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 estimate1.5 million m³range 578,874 - 3.6 million m³
In litres1.5 billionrange 578.9 million - 3.6 billion L
Olympic swimming pools581at 2,500 m³ each
Organic load, as people's raw sewage2.2 millionperson-days of untreated BOD

Assumed spill rate while spilling: 133.8 - 843.2 L/s (central 335.8 L/s), from a dry-weather flow of 133.8 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 23,155 kg130,796 kg729,707 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 60,782 kg617,647 kg2.6 million kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 1,100 kg9,156 kg33,931 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 695 kg3,779 kg19,702 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 57.9 trillion organisms1.5 × 10¹⁵ organisms3.6 × 10¹⁶ 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.

Barrow-in-Furness WwTW

Storm tank at sewage works · discharges to Walney Channel (estuarine waters)

Spills 2025
64 (899 hours) · down 33% on 2024
Spills 2024
95 (1,103 hours)
Long-term average
74.0 spills a year (monitored since 2018)
Monitor uptime
100% of the year
High-spill reason (company)
Data collection - Confirmed exceptional weather
Investigation
No investigation activity in reporting period
Improvement
No improvement action in reporting period
Bathing water
Walney Biggar Bank; Walney West Shore; Walney Sandy Gap
Shellfish water
Walney; Roosebeck
WFD catchment
Morecambe Bay - Coastal (GB641211171000)
Outlet location
SD2200068190 (OS grid reference) · View on Apple Maps
EA ID / permit
UUP00195 · 017470166 · company name: Barrow-in-Furness Wastewater Treatment Works (BARFU) (017470166)

Barrow-in-Furness WwTW

Inlet overflow at sewage works · discharges to Walney Channel (estuarine waters)

Spills 2025
49 (303 hours) · down 17% on 2024
Spills 2024
59 (341 hours)
Long-term average
62.0 spills a year (monitored since 2017)
Monitor uptime
100% of the year
High-spill reason (company)
Data collection - Confirmed exceptional weather
Investigation
No investigation activity in reporting period
Improvement
No improvement action in reporting period
Bathing water
Walney Biggar Bank; Walney West Shore; Walney Sandy Gap
Shellfish water
Walney; Roosebeck
WFD catchment
Morecambe Bay - Coastal (GB641211171000)
Outlet location
SD2200068190 (OS grid reference) · View on Apple Maps
EA ID / permit
UUP00196 · 017470166 · company name: Barrow-in-Furness Wastewater Treatment Works (BARFU) (017470166)

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.