Changelog

Every version of this site, what changed, and why. The current version is 2.0.0, corrected on 2 October 2026. The first version's pages, paper and model are kept in the archive.

Version 2.0.0: Corrected, 2 October 2026

An outside review found errors in the figures this site and its briefing paper published. We checked every claim against our own code and against public sources. Several were wrong. We have retired them, kept the originals available, and rebuilt the site so that every number carries a source or is labelled as an estimate with its working.

From the author. This site and its briefing paper were built with an AI assistant in March 2026. I accepted the figures it produced without checking them against the sources, and I sent the paper to elected members and public bodies. Several of those figures were wrong. That was my responsibility. The old site, paper and model stay available under Archive, marked as corrected, so you can see exactly what was published and exactly what was wrong. What has not changed is the point: sewage and slurry are resources for energy and for work, and the people who live with the sewage should not be the ones who pay for it.

Added

• A version number, this changelog, and a 'corrected' ribbon on the logo.
• Sources & estimates (/figures, and /figures.csv): every number on the site, whether it is sourced, live or an estimate, where it comes from, and the working for each estimate.
• Archive (/archive): the original briefing paper, the original model (every affected cell marked), the original site text in English and Welsh, and the original data the site served, each with a checksum so you can see they have not been altered.
• Live overflow data now reads every page of Welsh Water's services (2,340 monitored sites and 2,362 live overflows, not the first 2,000 of each), and says when it was fetched.
• Welsh Water's own regulatory data on sludge and energy, with table references.
• Questions in place of asks: which overflows are being fixed and when; which outflows near bathing waters are disinfected; where the £44.72m Ofwat package goes and who ultimately pays; why heat from sludge digestion goes unused; why energy self-sufficiency is stuck below target; whether farm slurry could be carried to Welsh Water's digesters with the cake coming back; whether heat recovery on dairy farms is a quicker first step; and how farm pollution is found and stopped.
• Automated checks that run before any change: unit and arithmetic checks, that every figure has a source or its working, that the home page, the sources page and the data feed show the same numbers, and that retired claims cannot return to the live pages.

Kept

• The live overflow map and the worst-site list (now complete).
• Bathing-water classifications and the map (2024 classifications are shown; 2025 results are quoted in the figures).
• The idea: waste as a resource for energy and for work, and accountability that does not fall on the people suffering the sewage.

Still to do

• Welsh text: the Welsh on this site was written by Claude on 2 October 2026, at the author's request, and has not yet been checked by a Welsh speaker; the Welsh footer says so. A page with no Welsh yet shows the English with a note. The original Welsh of version 1 is preserved under Archive and is not reused where the claim changed. The terms Claude chose, and the ones it was unsure of, are in docs/welsh-retranslation.md.
• Bathing-water map still shows the 2024 classifications (2025: 78 of 112 Excellent).
• The briefing paper has not been reissued. The original is available, marked superseded.

Notes

• The /api/works response no longer includes an 'energy' block, and /api/stats no longer includes wastePerSecond or the fuel-price list. The previous responses are preserved verbatim under Archive.

Retired or corrected (23)

Each is quoted as it was published, with why it failed and the evidence: all 23 retired claims.

Version 1.0.0: First published, 24 March 2026

The first site, with the briefing paper (dated March 2026), the Economic Impact Model, live overflow map, energy and unemployment sections, and a Welsh-language version.

Notes

• Superseded by 2.0.0. Everything published in 1.0.0 remains available under Archive.

Retired and corrected claims

23 claims from version 1.0.0 that we retired or corrected in version 2.0.0. Each is quoted as it was published, with why it failed and the evidence. Nothing was removed without being listed here.

• £2.06 flushed away every second2 October 2026

  Retired in version 2.0.0 (wrong). Derived from the claim above: (718,803 − 69,000 MWh) × £100/MWh ÷ seconds in a year.

• 2,800+ jobs waiting to be created2 October 2026

  Retired in version 2.0.0 (unsupported). The v1 model's permanent job count was 1,400 (824 direct × a 1.7 multiplier).

• 2.4 times Welsh Water's total energy use2 October 2026

  Retired in version 2.0.0 (wrong). It divided the 718,803 MWh by a 300,000 MWh 'total energy use' that had no source.

• 25p a week back to every household2 October 2026

  Retired in version 2.0.0 (unsupported). It was £17.6m of 'net benefit' ÷ 1.35 million households.

• 718,803 MWh of untapped energy2 October 2026

  Retired in version 2.0.0 (wrong). The number was 3,938,648 (the sum of Welsh Water's catchment 'population' layer, close to its 3.96 million population equivalent) × 0.5 kWh per person.

• 74,310 people claiming unemployment benefits2 October 2026

  Retired in version 2.0.0 (unsupported). The live query to the ONS service had a wrong parameter and never returned data, so the page showed hard-coded approximate figures labelled January 20.

• 82 years of sewage spilled in 20242 October 2026

  Retired in version 2.0.0 (misleading). It was the sum of spill hours across all overflow sites divided by 8,760.

• A £40m fine, spread over five years2 October 2026

  Retired in version 2.0.0 (misleading). The 2024 case ended with a nominal penalty of £1 and a £39.4m redress package (bill reductions and money the company absorbed).

• A £46m annual energy bill2 October 2026

  Retired in version 2.0.0 (out of date). It came from a 2021 trade-press report.

• Bathing water quality at a 7-year low2 October 2026

  Retired in version 2.0.0 (unsupported). We could not find this in the source.

• Farm digesters stop river pollution at source2 October 2026

  Retired in version 2.0.0 (unsupported). Digestate keeps its nitrogen and phosphorus (Welsh Water's own plan says the nutrient content of its product 'remains little-changed') and is spread u.

• Five Fords produces only 8% of energy demand2 October 2026

  Retired in version 2.0.0 (misleading). Welsh Water's March 2025 release is forward-looking and combines biomethane, combined heat and power, and solar panels: 'around 8% of Welsh Water's an.

• Model: Welsh Water digests 15-20%2 October 2026

  Retired in version 2.0.0 (wrong). Welsh Water's audited tables show 98.2% (2025-26) and 98.5% (2024-25)..

• No subsidy is required2 October 2026

  Retired in version 2.0.0 (wrong). Welsh Water's own sludge energy earned £6.6m of renewable-energy subsidies in 2025-26 (Renewables Obligation Certificates £2.1m and Renewable Heat Inc.

• Northumbrian creates 3,000 jobs a year2 October 2026

  Retired in version 2.0.0 (misleading). It is a company projection for its whole £2.6bn programme (pipes, sewers and treatment), not for digestion.

• Ofwat rates Northumbrian 32% more efficient2 October 2026

  Retired in version 2.0.0 (misattributed). The sentence comes from Northumbrian's own planning document, built on Ofwat's 2019 models.

• Processing sludge makes the water clean2 October 2026

  Retired in version 2.0.0 (wrong). Sludge is only the solids a works takes out of the flow, and it is removed from the works by design; dumping at sea ended in 1998.

• The highest rate of homes off gas in Britain2 October 2026

  Retired in version 2.0.0 (wrong). DESNZ's figures are for domestic properties without a gas meter (they include second homes and empty properties), not homes.

• The investment would be self-financing2 October 2026

  Retired in version 2.0.0 (unsupported). On the model's own inputs, £940m of capital at its 4.5% bond rate costs £42m a year in interest alone, against £27m of revenue and savings it reported.

• The model's energy, capital and revenue figures2 October 2026

  Retired in version 2.0.0 (wrong). One formula (cell B6) divided methane energy by 1,000 when million m³ × kWh/m³ is already GWh.

• The spill totals and the worst-offenders list2 October 2026

  Retired in version 2.0.0 (corrected). The data service returns at most 2,000 records a request and we never asked for the rest.

• Welsh Water digests only a fraction of its sludge2 October 2026

  Retired in version 2.0.0 (wrong). 98.2% of Welsh Water's sludge went through advanced anaerobic digestion in 2025-26 (98.5% in 2024-25; that is the company's reported result, not its t.

• Why is Welsh Water not doing what Northumbrian does?2 October 2026

  Retired in version 2.0.0 (misleading). On the share of sludge digested the gap is 98.2% (Welsh Water, regulatory table) against Northumbrian's own claim of 100%.