Storm overflow register · Northumbrian Water

Bran Sands Ww Treatment Works sewage works: storm overflow spills 2025

Bran Sands Ww Treatment Works sewage treatment works, run by Northumbrian Water, has 1 monitored storm overflow discharging to Dabholm Gut. In 2025 it recorded 70 spills totalling 322 hours, against 102 spills and 542 hours in 2024. By hours spilling, it ranks 63 of 183 Northumbrian Water works, where 1 spilled longest.

Works size: 385,324 population equivalent (MIDDLESBOROUGH 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.

JanFebMarAprMayJunJulAugSepOctNovDecBran Sands Ww…3 spills, 22.8 h, 1 Jan to 2 Jan20 spills, 45.1 h, 5 Jan to 7 Jan2 spills, 10.6 h, 26 Jan to 27 Jan2 spills, 0.2 h, 4 Feb to 4 Feb4 spills, 1.8 h, 10 Feb to 10 Feb7 spills, 2.7 h, 20 Feb to 20 Feb6 spills, 0.3 h, 23 Feb to 23 Feb3 spills, 1.5 h, 27 Feb to 27 Feb7 spills, 5.1 h, 12 Mar to 13 Mar3 spills, 3.9 h, 22 Mar to 23 Mar30 Mar 2025 23:39 GMT, 8 min15 May 2025 14:16 GMT, 8 min22 May 2025 15:13 GMT, 4 min3 spills, 1.4 h, 24 May to 24 May2 spills, 0.2 h, 29 May to 29 May1 Jun 2025 16:50 GMT, 5 min9 spills, 1.9 h, 6 Jun to 6 Jun6 spills, 2.3 h, 7 Jun to 7 Jun4 spills, 4.9 h, 2 Jul to 2 Jul2 spills, 3.3 h, 15 Jul to 15 Jul28 spills, 11.9 h, 18 Jul to 19 Jul23 Jul 2025 12:35 GMT, 2.1 h1 Aug 2025 01:50 GMT, 4 min4 spills, 0.9 h, 4 Aug to 4 Aug27 Aug 2025 18:44 GMT, 50 min3 spills, 0.2 h, 28 Aug to 28 Aug31 Aug 2025 18:02 GMT, 93 min1 Sep 2025 14:32 GMT, 88 min2 spills, 1.9 h, 3 Sep to 3 Sep7 spills, 1 h, 4 Sep to 4 Sep13 Sep 2025 23:56 GMT, 92 min7 spills, 30.6 h, 20 Sep to 21 Sep28 Sep 2025 05:20 GMT, 16 min7 spills, 4.4 h, 3 Oct to 3 Oct5 spills, 2.8 h, 19 Oct to 20 Oct4 spills, 0.8 h, 23 Oct to 23 Oct5 spills, 1 h, 4 Nov to 4 Nov11 Nov 2025 14:17 GMT, 3 min64 spills, 38.2 h, 12 Nov to 15 Nov17 Nov 2025 06:23 GMT, 5 min50 spills, 17.4 h, 18 Nov to 20 Nov5 spills, 19.4 h, 24 Nov to 25 Nov26 Nov 2025 18:30 GMT, 3.9 h3 spills, 3.3 h, 28 Nov to 28 Nov41 spills, 22.5 h, 29 Nov to 1 Dec2 spills, 12.5 h, 4 Dec to 6 Dec7 Dec 2025 16:47 GMT, 2.8 h14 spills, 7.6 h, 9 Dec to 9 Dec30 spills, 17.2 h, 15 Dec to 16 Dec53 spills, 5.5 h, 18 Dec to 18 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.

0500k1M1.5M2MJan 2025: 79 h spilling ≈ 518,281 m³ (range 206,442-1.3 million m³)JanFeb 2025: 6.4 h spilling ≈ 42,255 m³ (range 16,831-106,082 m³)FebMar 2025: 9.2 h spilling ≈ 60,741 m³ (range 24,194-152,493 m³)MarApr 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AprMay 2025: 1.8 h spilling ≈ 11,884 m³ (range 4,734-29,836 m³)MayJun 2025: 4.3 h spilling ≈ 28,390 m³ (range 11,308-71,274 m³)JunJul 2025: 22 h spilling ≈ 146,571 m³ (range 58,382-367,973 m³)JulAug 2025: 3.5 h spilling ≈ 23,108 m³ (range 9,204-58,014 m³)AugSep 2025: 37 h spilling ≈ 242,965 m³ (range 96,778-609,973 m³)SepOct 2025: 7.9 h spilling ≈ 52,158 m³ (range 20,776-130,945 m³)OctNov 2025: 104 h spilling ≈ 685,320 m³ (range 272,977-1.7 million m³)NovDec 2025: 47 h spilling ≈ 312,949 m³ (range 124,654-785,672 m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
5 Jan 2025, 09:10Bran Sands Ww Treatment Works1.7 days106,333 - 670,197 m³
20 Sep 2025, 08:00Bran Sands Ww Treatment Works1.2 days76,704 - 483,448 m³
1 Jan 2025, 00:00Bran Sands Ww Treatment Works22.7 h59,741 - 376,537 m³
29 Nov 2025, 15:35Bran Sands Ww Treatment Works13.9 h36,423 - 229,569 m³
24 Nov 2025, 05:48Bran Sands Ww Treatment Works12.9 h33,881 - 213,546 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 estimate2.1 million m³range 845,755 - 5.3 million m³
In litres2.1 billionrange 845.8 million - 5.3 billion L
Olympic swimming pools849at 2,500 m³ each
Organic load, as people's raw sewage3.2 millionperson-days of untreated BOD

Assumed spill rate while spilling: 730.5 - 4,604.3 L/s (central 1,834.0 L/s), from a dry-weather flow of 730.5 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 33,830 kg191,097 kg1.1 million kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 88,804 kg902,403 kg3.8 million kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 1,607 kg13,377 kg49,575 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 1,015 kg5,521 kg28,785 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 84.6 trillion organisms2.1 × 10¹⁵ organisms5.3 × 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.

Bran Sands Ww Treatment Works

Inlet overflow at sewage works · discharges to Dabholm Gut

Spills 2025
70 (322 hours) · down 31% on 2024
Spills 2024
102 (542 hours)
Long-term average
101.0 spills a year (monitored since 2020)
Monitor uptime
100% of the year
High-spill reason (company)
Not asset maintenance - Hydraulic capacity
Investigation
Env Act (SODRP) investigation ongoing, Operational investigation completed
Improvement
No improvement action in reporting period
WFD catchment
Tees Estuary (S Bank) (GB103025072320)
Outlet location
NZ5614024090 (OS grid reference) · View on Apple Maps
EA ID / permit
NWL00184 · 254/1920

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 Northumbrian 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.