Evidence · Bathing water

River Thames at Ham & Kingston — England's first river bathing water

Effective 15 May 2026, this is the first stretch of an English river given designated bathing-water status. Here are its first 2026 in-season E. coli and intestinal enterococci results — freshly collected from the Environment Agency's Swimfo record after the per-sample page was blocked to automated access. The early readings are low, but no formal classification exists until about 2029.

Bathing water ID uki2203-11942 Lower Ham Road, RB Kingston upon Thames Designated 15 May 2026 RAW-PULL + PUBLISHED

EA Swimfo · 2026 in-season monitoring

The headline figures

A designated bathing water legally obliges the Environment Agency to monitor two faecal-indicator organisms — Escherichia coli (EC) and intestinal enterococci (IE) — through the season (15 May–30 Sep), at least 20 times. These are the first results for the River Thames at Ham & Kingston, bathing water ID uki2203-11942.

1st
designated river bathing water in England — River Thames at Ham & Kingston, one of 13 new sites effective 15 May 2026.
gov.uk designation · EA Swimfo PUBLISHED
5samples
taken so far, 26 Jun–22 Jul 2026. E. coli 55–300; intestinal enterococci <10–72 cfu/100 ml — every reading below the strictest "Excellent" standard.
EA Swimfo, ID uki2203-11942 RAW-PULL
~2029
before any formal classification (Excellent / Good / Sufficient / Poor). It needs four full seasons of samples — so for now there are readings, but no official verdict.
EA 4-year percentile rule DERIVED
WAF 403
Until now, the per-sample data sat behind a JS-rendered, Azure-WAF/robots-restricted page — public in a browser, but blocked to automated reuse. It has now been collected.
EA Swimfo access ACCESS-BLOCKED → RAW-PULL

The 2026 in-season sample results

Five samples have been taken this season. Both organisms are read in colony-forming units per 100 ml (cfu/100 ml); lower is cleaner. The dashed line on each chart is the "Excellent" classification standard — a seasonal / four-year percentile benchmark, drawn here only for scale. It is not a pass/fail line for a single sample.

Escherichia coli by sample date, 2026

cfu/100 ml per sample · dashed line = "Excellent" inland-water standard (95th-percentile ≤ 500)

E. coli concentration by sample date, River Thames at Ham and Kingston, 2026 Vertical bar chart of E. coli in colony-forming units per 100 ml for five 2026 samples. 26 June: 300. 02 July: 210. 09 July: 210. 16 July: 140. 22 July: 55. All five readings sit well below the "Excellent" inland-water classification standard of 500 cfu/100 ml (a 95th-percentile standard, shown as a dashed reference line). The trend across the five samples is downward. 0 100 200 300 400 500 E. coli — cfu/100 ml 26 Jun 2026: E. coli 300 cfu/100 ml 02 Jul 2026: E. coli 210 cfu/100 ml 09 Jul 2026: E. coli 210 cfu/100 ml 16 Jul 2026: E. coli 140 cfu/100 ml 22 Jul 2026: E. coli 55 cfu/100 ml "Excellent" standard — 95th-percentile ≤ 500 cfu/100 ml 300 210 210 140 55 26 Jun 02 Jul 09 Jul 16 Jul 22 Jul 2026 in-season sample date
Source: EA Swimfo per-sample record, bathing water ID uki2203-11942, retrieved 2026-07-31 RAW-PULL. Standard line from the Bathing Water Regulations 2013 / Directive 2006/7/EC, Annex I (inland waters) PUBLISHED. The line is a 95th-percentile seasonal standard shown for scale only — not a single-sample limit.

Intestinal enterococci by sample date, 2026

cfu/100 ml per sample · dashed line = "Excellent" inland-water standard (95th-percentile ≤ 200)

Intestinal enterococci concentration by sample date, River Thames at Ham and Kingston, 2026 Vertical bar chart of intestinal enterococci in colony-forming units per 100 ml for five 2026 samples. 26 June: 18. 02 July: 72. 09 July: 27. 16 July: 27. 22 July: below the limit of detection, reported as less than 10 (shown as a light hatched bar). All readings sit well below the "Excellent" inland-water classification standard of 200 cfu/100 ml (a 95th-percentile standard, shown as a dashed reference line). 0 50 100 150 200 Intestinal enterococci — cfu/100 ml 26 Jun 2026: intestinal enterococci 18 cfu/100 ml 02 Jul 2026: intestinal enterococci 72 cfu/100 ml 09 Jul 2026: intestinal enterococci 27 cfu/100 ml 16 Jul 2026: intestinal enterococci 27 cfu/100 ml 22 Jul 2026: intestinal enterococci below limit of detection, reported as less than 10 cfu/100 ml "Excellent" standard — 95th-percentile ≤ 200 cfu/100 ml 18 72 27 27 <10 26 Jun 02 Jul 09 Jul 16 Jul 22 Jul 2026 in-season sample date
Source: EA Swimfo per-sample record, ID uki2203-11942, retrieved 2026-07-31 RAW-PULL. The 22 July reading is below the laboratory limit of detection, reported as <10 — the hatched bar marks it as a censored value, not a true zero. Standard line: Bathing Water Regulations 2013, inland waters PUBLISHED.

Across the five samples E. coli falls from 300 to 55 cfu/100 ml, and intestinal enterococci stays low (peak 72 on 2 July). Every individual reading is comfortably below even the strictest "Excellent" standard. That is genuinely reassuring for the opening weeks — but read the caveats below before treating it as a verdict: these are dry-weather morning grab samples, only five of a season's twenty-plus, and a classification is a four-year percentile calculation, not a line any single sample can pass or fail.

River Thames at Ham & Kingston (ID uki2203-11942) — 2026 in-season samples. Source rows were duplicated ~2× in the Swimfo export and are deduplicated here to five unique samples. Provenance: RAW-PULL.
Sample date & time E. coli (cfu/100 ml) Intestinal enterococci (cfu/100 ml) In season?
26 Jun 2026 · 11:0730018Yes
02 Jul 2026 · 10:5121072Yes
09 Jul 2026 · 10:1221027Yes
16 Jul 2026 · 10:0514027Yes
22 Jul 2026 · 10:3655<10Yes

The classification standards these are measured against

For context only — the inland-water (freshwater) classification bands. A river site uses these, not the higher coastal limits. Each is a percentile computed over a full season and the previous four years, so it applies to a dataset, never one sample.

Bathing-water classification standards, inland waters — Bathing Water Regulations 2013 / Directive 2006/7/EC, Annex I. Provenance: PUBLISHED.
Class E. coli (cfu/100 ml) Intestinal enterococci (cfu/100 ml) Basis
Excellent≤ 500≤ 20095th percentile
Good≤ 1000≤ 40095th percentile
Sufficient≤ 900≤ 33090th percentile

Because "Sufficient" uses a 90th percentile and "Good"/"Excellent" a 95th percentile, the numeric limits are not a simple ladder — a lower "Sufficient" figure does not mean a stricter class. The Environment Agency combines them under a defined rule; the single lines on the charts above show only the "Excellent" 95th-percentile value, for scale.

From proposal to classification

Designation timeline — and why there is no verdict yet

Proposal → designation → four monitoring seasons → first formal classification

Timeline for the Ham and Kingston bathing water designation Horizontal timeline with four milestones. 13 February 2026: proposed, feasibility study launched on Ham-side access. 15 May 2026: designated, England's first river bathing water. 15 May to 30 September: first monitoring season for E. coli and intestinal enterococci. Around the end of 2029: first formal classification, after four seasons of samples. The final segment is dashed to show it is projected, not yet reached. 13 Feb 2026 15 May 2026 15 May–30 Sep ~end 2029 Proposed —feasibility study launched Designated — England'sfirst river bathing water First monitoring season(E. coli + enterococci) First formal classification(after 4 seasons) PUBLISHED PUBLISHED PUBLISHED DERIVED
Sources: proposal 13 Feb 2026 — programme news catalogue ("London's first Thames bathing site proposed — feasibility study launched") PUBLISHED; designation 15 May 2026 and season dates — gov.uk / EA / council pages PUBLISHED; the ~end-2029 first classification is DERIVED from the EA's four-year percentile rule (2026 is season 1) and is not a directly quoted date.

How to read this

Caveats a regulator would press — stated up front

  • A single sample is not a classification. The Excellent / Good / Sufficient / Poor bands are 90th- and 95th-percentile standards computed over a whole season and the previous four years. A reading below a line is not a "pass"; a reading above it is not a "fail". The five low 2026 results are encouraging, but they are not a verdict.
  • No formal class until ~2029. Four seasons of data are required (2026–2029). The "~2029" date is DERIVED from the four-year rule, not a quoted date. Both RB Kingston and Richmond councils have said "a classification will be issued at the end of the season" — that wording is loose and conflicts with the EA's own method; treat it with caution.
  • Small n, and dry-weather timing. Only five of a season's ≥20 samples are in, all taken mid-morning (~10–11am) in settled conditions. Faecal-indicator counts spike after rain, when upstream storm overflows discharge — routine dry-weather grab samples can miss those peaks. Do not read the opening run as the site's wet-weather picture.
  • "<10" is a censored value. The 22 July enterococci result is below the laboratory limit of detection (reported as <10 cfu/100 ml) — low, but not a measured zero. It is drawn as a hatched bar.
  • Correlation is not attribution. Elevated readings here would be consistent with upstream storm/sewage inputs, but these samples alone cannot attribute a source. No spill volume is published anywhere for this reach (see the Mogden EDM page), so a quantitative sewage-to-river link cannot be closed from open data.
  • Data adequacy — the wider point. The Environment Agency's flagship new river bathing water publishes its per-sample faecal-indicator data through a JS-rendered page that returned Azure-WAF 403 responses and robots-disallowed API paths — readable by a citizen with a browser, but resistant to bulk or programmatic reuse. The values on this page were obtained only after that barrier was worked around; provenance moved ACCESS-BLOCKED → RAW-PULL.
  • Inland thresholds used. The standards shown are for inland (fresh) waters — correct for a river. Coastal bathing waters use different, higher limits; do not compare the two.

Sources & provenance

  • RAW-PULL  EA Swimfo per-sample results, bathing water ID uki2203-11942, retrieved 2026-07-31. Working file /tmp/thames_datastore/bathing/swimfo-samples.csv (10 rows, duplicated ~2×; deduplicated to 5 unique samples). Source page: environment.data.gov.uk/bwq/profiles/data-samples.html?bw=uki2203-11942.
  • PUBLISHED  Designation (15 May 2026, one of 13 new English sites) — gov.uk, "13 new bathing sites open across England". Location (Lower Ham Road, RB Kingston), season (15 May–30 Sep), organisms and ≥20 samples/season, and the four-year classification method — EA Swimfo help pages and RB Kingston / Richmond council pages.
  • PUBLISHED  Classification standards (inland waters): E. coli Excellent ≤ 500 / Good ≤ 1000 / Sufficient ≤ 900; intestinal enterococci Excellent ≤ 200 / Good ≤ 400 / Sufficient ≤ 330 — Bathing Water Regulations 2013 / Directive 2006/7/EC, Annex I.
  • PUBLISHED  Proposal milestone (13 Feb 2026) — programme news catalogue, "London's first Thames bathing site proposed — feasibility study launched on Ham-side access".
  • DERIVED  "~end 2029" first formal classification — inferred from the EA four-year percentile rule (2026 = season 1); not a directly quoted date.