Storm overflow register · Yorkshire Water

Ripon Wpc Works sewage works: storm overflow spills 2025

Ripon Wpc Works sewage treatment works, run by Yorkshire Water, has 2 monitored storm overflows discharging to River Ure. In 2025 they recorded 104 spills totalling 457 hours, against 104 spills and 753 hours in 2024. By hours spilling, it ranks 103 of 283 Yorkshire Water works, where 1 spilled longest.

Works size: 20,909 population equivalent (RIPON 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.

JanFebMarAprMayJunJulAugSepOctNovDecRipon Wpc Works259 spills, 9.8 h, 1 Jan to 2 Jan458 spills, 16.9 h, 5 Jan to 7 Jan88 spills, 3.2 h, 27 Jan to 28 Jan10 spills, 3.8 h, 15 Jul to 16 Jul5 spills, 5.3 h, 19 Jul to 19 Jul10 spills, 4.9 h, 20 Jul to 21 Jul8 spills, 0.4 h, 4 Sep to 4 Sep13 Sep 2025 17:10 GMT, 2 min6 spills, 0.2 h, 17 Sep to 17 Sep112 spills, 23.8 h, 20 Sep to 21 Sep8 spills, 2.8 h, 28 Sep to 28 Sep54 spills, 11.5 h, 3 Oct to 4 Oct11 spills, 7.5 h, 19 Oct to 20 Oct10 spills, 3.2 h, 11 Nov to 12 Nov15 spills, 5.6 h, 12 Nov to 13 Nov128 spills, 35.3 h, 14 Nov to 16 Nov57 spills, 6.7 h, 19 Nov to 19 Nov39 spills, 5.7 h, 23 Nov to 24 Nov8 spills, 0.9 h, 28 Nov to 28 Nov192 spills, 28.9 h, 29 Nov to 2 Dec884 spills, 76.8 h, 4 Dec to 12 Dec60 spills, 7.5 h, 15 Dec to 15 Dec129 spills, 13.3 h, 17 Dec to 19 Dec19 spills, 3.6 h, 22 Dec to 22 DecRipon Wpc Works71 spills, 20 h, 1 Jan to 2 Jan59 spills, 36.3 h, 5 Jan to 7 Jan3 spills, 3 h, 24 Jan to 24 Jan18 spills, 11.8 h, 26 Jan to 28 Jan6 spills, 1.8 h, 20 Feb to 20 Feb8 spills, 4 h, 23 Feb to 23 Feb12 spills, 5.6 h, 22 Mar to 23 Mar25 Mar 2025 04:32 GMT, 2 min2 spills, 2.7 h, 24 May to 24 May4 spills, 1.7 h, 26 May to 27 May2 spills, 0.7 h, 30 May to 30 May2 spills, 0.7 h, 3 Jun to 3 Jun2 spills, 1 h, 6 Jun to 6 Jun2 Jul 2025 10:54 GMT, 28 min3 spills, 2.7 h, 15 Jul to 15 Jul3 spills, 2.1 h, 19 Jul to 19 Jul4 spills, 2.7 h, 20 Jul to 20 Jul21 Jul 2025 15:00 GMT, 20 min22 Jul 2025 13:18 GMT, 32 min2 spills, 0.9 h, 4 Sep to 4 Sep11 Sep 2025 14:14 GMT, 40 min12 Sep 2025 12:24 GMT, 12 min13 Sep 2025 15:16 GMT, 60 min4 spills, 15.3 h, 20 Sep to 21 Sep3 spills, 1.9 h, 27 Sep to 28 Sep1 Oct 2025 06:58 GMT, 58 min6 spills, 6.1 h, 2 Oct to 3 Oct7 spills, 4.7 h, 19 Oct to 20 Oct3 spills, 2.3 h, 11 Nov to 11 Nov4 spills, 0.7 h, 12 Nov to 12 Nov7 spills, 6.3 h, 14 Nov to 15 Nov4 spills, 0.6 h, 19 Nov to 19 Nov5 spills, 2.4 h, 23 Nov to 23 Nov28 Nov 2025 13:02 GMT, 52 min29 Nov 2025 18:18 GMT, 3 h5 spills, 3.6 h, 1 Dec to 1 Dec3 spills, 1.7 h, 4 Dec to 4 Dec7 spills, 2.9 h, 5 Dec to 5 Dec8 spills, 6.3 h, 6 Dec to 7 Dec4 spills, 11 h, 9 Dec to 10 Dec2 spills, 2.4 h, 15 Dec to 15 Dec2 spills, 6 h, 17 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.

050k100k150kJan 2025: 101 h spilling ≈ 36,185 m³ (range 14,413-90,843 m³)JanFeb 2025: 5.8 h spilling ≈ 2,078 m³ (range 828-5,217 m³)FebMar 2025: 5.6 h spilling ≈ 2,006 m³ (range 799-5,037 m³)MarApr 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AprMay 2025: 5.1 h spilling ≈ 1,827 m³ (range 728-4,587 m³)MayJun 2025: 1.7 h spilling ≈ 609 m³ (range 243-1,529 m³)JunJul 2025: 23 h spilling ≈ 8,168 m³ (range 3,254-20,507 m³)JulAug 2025: 0.0 h spilling ≈ 0.0 m³ (range 0.0-0.0 m³)AugSep 2025: 47 h spilling ≈ 16,874 m³ (range 6,721-42,363 m³)SepOct 2025: 31 h spilling ≈ 11,035 m³ (range 4,395-27,703 m³)OctNov 2025: 86 h spilling ≈ 30,667 m³ (range 12,215-76,992 m³)NovDec 2025: 152 h spilling ≈ 54,420 m³ (range 21,677-136,624 m³)Dec
Cubic metres (m³), estimate. Hours are measured by the event duration monitor.

Longest single spills

Started (GMT)OverflowDurationEstimated volume
5 Jan 2025, 16:00Ripon Wpc Works1.2 days4,053 - 25,544 m³
20 Sep 2025, 15:50Ripon Wpc Works10.4 h1,484 - 9,354 m³
14 Nov 2025, 21:10Ripon Wpc Works7.4 h1,061 - 6,686 m³
3 Oct 2025, 13:46Ripon Wpc Works7.3 h1,046 - 6,596 m³
1 Jan 2025, 18:54Ripon Wpc Works6.6 h947 - 5,966 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 estimate163,834 m³range 65,259 - 411,312 m³
In litres163.8 millionrange 65.3 million - 411.3 million L
Olympic swimming pools66at 2,500 m³ each
Organic load, as people's raw sewage245,751person-days of untreated BOD

Assumed spill rate while spilling: 39.6 - 249.8 L/s (central 99.5 L/s), from a dry-weather flow of 39.6 L/s.

Pollutant releasedLowCentralHighConcentration used (low / typical / high)
BOD₅ (organic load) 2,610 kg14,745 kg82,262 kg 40 / 90 / 200 mg/L
Low/high: Europe range, Ellis & Jenkins 2005; typical: UK, Ellis & Jenkins 2005 (both via botturi)
Suspended solids 6,852 kg69,629 kg296,556 kg 105 / 425 / 721 mg/L
Low/high: Europe range; typical: UK, Ellis & Jenkins 2005 (via botturi)
Ammonium-N 124 kg1,032 kg3,825 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 78 kg426 kg2,221 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 6.5 trillion organisms163.8 trillion organisms4.1 × 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.

Ripon Wpc Works

Storm tank at sewage works · discharges to River Ure

Spills 2025
46 (278 hours) · down 21% on 2024
Spills 2024
58 (601 hours)
Long-term average
59.7 spills a year (monitored since 2020)
Monitor uptime
100% of the year
High-spill reason (company)
Not asset maintenance - hydraulic capacity
Investigation
UWWTR investigation ongoing, Operational investigation completed
Improvement
No improvement action in reporting period
WFD catchment
Skell from River Laver to River Ure (GB104027064140)
Outlet location
SE3241570792 (OS grid reference) · View on Apple Maps
EA ID / permit
YWS00281 · 27/22/0052 · company name: RIPON/STW

Ripon Wpc Works

Inlet overflow at sewage works · discharges to River Ure

Spills 2025
58 (180 hours) · up 26% on 2024
Spills 2024
46 (152 hours)
Long-term average
23.4 spills a year (monitored since 2020)
Monitor uptime
100% of the year
High-spill reason (company)
Not asset maintenance - hydraulic capacity
Investigation
UWWTR investigation ongoing, Operational investigation completed
Improvement
No improvement action in reporting period
WFD catchment
Skell from River Laver to River Ure (GB104027064140)
Outlet location
SE3237070810 (OS grid reference) · View on Apple Maps
EA ID / permit
YWS00282 · 27/22/0052 · company name: RIPON/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 Yorkshire 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.