Headwaters upstream of Watford sewage treatment works
EA name: HEADWATERS U/S WATFORD STW
Environment Agency sampling point AN-USWAFORD · Freshwater - rivers · listed as open (“open” does not mean it is sampled now)
These are samples taken on a date, not live readings of the river. Results reach the Environment Agency's archive days to months after the sample is taken, so the newest here may be weeks or months old. FloodRadar does not grade them.
Where and when
- Last sampled
- 29 Jun 2026, 11:383 months ago · time as the Environment Agency records it (UK clock time; the source gives no time zone)
- Samples banked
- 27 since 27 Jun 2024 Imported periods: 1 Oct 2023 – 30 Sep 2026. Samples outside them are not shown here.
- Latest sample
- River / running surface water Monitoring (national agency policy)
- Where
- National Grid 459928, 269314As published, to the nearest 1 m. Open in a map
- River, by its own name
- Headwaters
- River, by the map
- Not placedIts name gives Headwaters; the only line close by, 1 m away, is Grand Union Canal and is not traced into it. The river map cannot say which watercourse this is.
- Next gauge downstream
- Not known
- Why it was sampled
- Monitoring (national agency policy) (27 samples)
5 visits found no water to sample (recorded as “No flow”).
Main measurements, river water
Dissolved oxygen
% saturation · code 9901 · %
87.2%
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 87.2 | 87.2% |
| 18 May 2026, 11:06 | 91.3 | 91.3% |
| 7 May 2026, 12:35 | 94.4 | 94.4% |
| 27 Apr 2026, 12:40 | 97.6 | 97.6% |
| 5 Mar 2026, 12:25 | 97.6 | 97.6% |
| 19 Feb 2026, 10:33 | 94.2 | 94.2% |
| 2 Jan 2026, 14:17 | 96.2 | 96.2% |
| 12 Dec 2025, 11:30 | 90.4 | 90.4% |
| 12 Nov 2025, 14:15 | 84.2 | 84.2% |
| 8 Aug 2025, 10:24 | 94.6 | 94.6% |
| 7 Jul 2025, 15:13 | 91.3 | 91.3% |
| 3 Jun 2025, 11:38 | 91.7 | 91.7% |
| 10 Apr 2025, 13:16 | 101.3 | 101.3% |
| 6 Mar 2025, 10:53 | 98.3 | 98.3% |
| 12 Feb 2025, 12:59 | 97.8 | 97.8% |
| 28 Jan 2025, 12:48 | 93 | 93% |
| 10 Dec 2024, 10:13 | 92.1 | 92.1% |
| 25 Nov 2024, 11:34 | 90.1 | 90.1% |
| 15 Oct 2024, 13:40 | 94 | 94% |
| 27 Sep 2024, 10:31 | 86.2 | 86.2% |
| 15 Jul 2024, 10:31 | 93.8 | 93.8% |
| 27 Jun 2024, 09:59 | 90.9 | 90.9% |
Dissolved oxygen
as O2 · code 9924 · mg/l
8.64 mg/l
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 8.64 | 8.64 mg/l |
| 18 May 2026, 11:06 | 10.3 | 10.3 mg/l |
| 7 May 2026, 12:35 | 10.2 | 10.2 mg/l |
| 27 Apr 2026, 12:40 | 9.99 | 9.99 mg/l |
| 5 Mar 2026, 12:25 | 11 | 11 mg/l |
| 19 Feb 2026, 10:33 | 12 | 12 mg/l |
| 2 Jan 2026, 14:17 | 12.8 | 12.8 mg/l |
| 12 Dec 2025, 11:30 | 10.3 | 10.3 mg/l |
| 12 Nov 2025, 14:15 | 8.99 | 8.99 mg/l |
| 8 Aug 2025, 10:24 | 9.58 | 9.58 mg/l |
| 7 Jul 2025, 15:13 | 9.22 | 9.22 mg/l |
| 3 Jun 2025, 11:38 | 9.7 | 9.7 mg/l |
| 10 Apr 2025, 13:16 | 11.1 | 11.1 mg/l |
| 6 Mar 2025, 10:53 | 12 | 12 mg/l |
| 12 Feb 2025, 12:59 | 12.4 | 12.4 mg/l |
| 28 Jan 2025, 12:48 | 11.5 | 11.5 mg/l |
| 10 Dec 2024, 10:13 | 11.1 | 11.1 mg/l |
| 25 Nov 2024, 11:34 | 10.3 | 10.3 mg/l |
| 15 Oct 2024, 13:40 | 10.2 | 10.2 mg/l |
| 27 Sep 2024, 10:31 | 9.14 | 9.14 mg/l |
| 15 Jul 2024, 10:31 | 9.73 | 9.73 mg/l |
| 27 Jun 2024, 09:59 | 8.91 | 8.91 mg/l |
Water temperature
code 0076 · °C
15.7 °C
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 15.7 | 15.7 °C |
| 18 May 2026, 11:06 | 10.1 | 10.1 °C |
| 7 May 2026, 12:35 | 11.7 | 11.7 °C |
| 27 Apr 2026, 12:40 | 14.2 | 14.2 °C |
| 5 Mar 2026, 12:25 | 9.8 | 9.8 °C |
| 19 Feb 2026, 10:33 | 4.9 | 4.9 °C |
| 2 Jan 2026, 14:17 | 3.4 | 3.4 °C |
| 12 Dec 2025, 11:30 | 9.6 | 9.6 °C |
| 12 Nov 2025, 14:15 | 12.3 | 12.3 °C |
| 8 Aug 2025, 10:24 | 14.7 | 14.7 °C |
| 7 Jul 2025, 15:13 | 14.8 | 14.8 °C |
| 3 Jun 2025, 11:38 | 12.7 | 12.7 °C |
| 10 Apr 2025, 13:16 | 11.1 | 11.1 °C |
| 6 Mar 2025, 10:53 | 6.6 | 6.6 °C |
| 12 Feb 2025, 12:59 | 5.3 | 5.3 °C |
| 28 Jan 2025, 12:48 | 6.3 | 6.3 °C |
| 10 Dec 2024, 10:13 | 7.2 | 7.2 °C |
| 25 Nov 2024, 11:34 | 9.3 | 9.3 °C |
| 15 Oct 2024, 13:40 | 11.5 | 11.5 °C |
| 27 Sep 2024, 10:31 | 12.6 | 12.6 °C |
| 15 Jul 2024, 10:31 | 13.6 | 13.6 °C |
| 27 Jun 2024, 09:59 | 16.2 | 16.2 °C |
pH
code 0061
8.14
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 8.14 | 8.14 |
| 18 May 2026, 11:06 | 8.01 | 8.01 |
| 7 May 2026, 12:35 | 8.06 | 8.06 |
| 27 Apr 2026, 12:40 | 8.04 | 8.04 |
| 5 Mar 2026, 12:25 | 7.75 | 7.75 |
| 19 Feb 2026, 10:33 | 7.68 | 7.68 |
| 2 Jan 2026, 14:17 | 8.14 | 8.14 |
| 12 Dec 2025, 11:30 | 7.7 | 7.7 |
| 12 Nov 2025, 14:15 | 6.87 | 6.87 |
| 8 Aug 2025, 10:24 | 8.22 | 8.22 |
| 7 Jul 2025, 15:13 | 8.09 | 8.09 |
| 3 Jun 2025, 11:38 | 8.01 | 8.01 |
| 10 Apr 2025, 13:16 | 8.15 | 8.15 |
| 6 Mar 2025, 10:53 | 7.98 | 7.98 |
| 12 Feb 2025, 12:59 | 7.9 | 7.9 |
| 28 Jan 2025, 12:48 | 7.57 | 7.57 |
| 10 Dec 2024, 10:13 | 7.65 | 7.65 |
| 25 Nov 2024, 11:34 | 7.4 | 7.4 |
| 15 Oct 2024, 13:40 | 7.79 | 7.79 |
| 27 Sep 2024, 10:31 | 7.37 | 7.37 |
| 15 Jul 2024, 10:31 | 7.91 | 7.91 |
| 27 Jun 2024, 09:59 | 7.96 | 7.96 |
Ammonia
ammoniacal nitrogen as N · code 0111 · mg/l
0.062 mg/l
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 0.062 | 0.062 mg/l |
| 18 May 2026, 11:06 | <0.03 | below 0.03 mg/l (not detected above this) |
| 7 May 2026, 12:35 | <0.03 | below 0.03 mg/l (not detected above this) |
| 27 Apr 2026, 12:40 | <0.03 | below 0.03 mg/l (not detected above this) |
| 5 Mar 2026, 12:25 | <0.03 | below 0.03 mg/l (not detected above this) |
| 19 Feb 2026, 10:33 | 0.036 | 0.036 mg/l |
| 2 Jan 2026, 14:17 | <0.03 | below 0.03 mg/l (not detected above this) |
| 12 Dec 2025, 11:30 | 0.069 | 0.069 mg/l |
| 12 Nov 2025, 14:15 | <0.03 | below 0.03 mg/l (not detected above this) |
| 8 Aug 2025, 10:24 | <0.03 | below 0.03 mg/l (not detected above this) |
| 7 Jul 2025, 15:13 | <0.03 | below 0.03 mg/l (not detected above this) |
| 3 Jun 2025, 11:38 | <0.03 | below 0.03 mg/l (not detected above this) |
| 10 Apr 2025, 13:16 | <0.03 | below 0.03 mg/l (not detected above this) |
| 6 Mar 2025, 10:53 | <0.03 | below 0.03 mg/l (not detected above this) |
| 12 Feb 2025, 12:59 | <0.03 | below 0.03 mg/l (not detected above this) |
| 28 Jan 2025, 12:48 | 0.063 | 0.063 mg/l |
| 10 Dec 2024, 10:13 | <0.03 | below 0.03 mg/l (not detected above this) |
| 25 Nov 2024, 11:34 | 0.054 | 0.054 mg/l |
| 15 Oct 2024, 13:40 | <0.03 | below 0.03 mg/l (not detected above this) |
| 27 Sep 2024, 10:31 | 0.1 | 0.1 mg/l |
| 15 Jul 2024, 10:31 | <0.03 | below 0.03 mg/l (not detected above this) |
| 27 Jun 2024, 09:59 | <0.03 | below 0.03 mg/l (not detected above this) |
Nitrate
as nitrogen (N) · code 0117 · mg/l
0.732 mg/l
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 0.732 | 0.732 mg/l |
| 18 May 2026, 11:06 | 0.856 | 0.856 mg/l |
| 7 May 2026, 12:35 | 1.19 | 1.19 mg/l |
| 27 Apr 2026, 12:40 | 1.69 | 1.69 mg/l |
| 5 Mar 2026, 12:25 | 9.68 | 9.68 mg/l |
| 19 Feb 2026, 10:33 | 12 | 12 mg/l |
| 2 Jan 2026, 14:17 | 11 | 11 mg/l |
| 12 Dec 2025, 11:30 | 16.9 | 16.9 mg/l |
| 12 Nov 2025, 14:15 | 1.1 | 1.1 mg/l |
| 8 Aug 2025, 10:24 | 0.626 | 0.626 mg/l |
| 7 Jul 2025, 15:13 | 1.2 | 1.2 mg/l |
| 3 Jun 2025, 11:38 | 1.69 | 1.69 mg/l |
| 10 Apr 2025, 13:16 | 4.69 | 4.69 mg/l |
| 6 Mar 2025, 10:53 | 8.29 | 8.29 mg/l |
| 12 Feb 2025, 12:59 | 8.07 | 8.07 mg/l |
| 28 Jan 2025, 12:48 | 9.67 | 9.67 mg/l |
| 10 Dec 2024, 10:13 | 13 | 13 mg/l |
| 25 Nov 2024, 11:34 | 15 | 15 mg/l |
| 15 Oct 2024, 13:40 | 7.87 | 7.87 mg/l |
| 27 Sep 2024, 10:31 | 15.9 | 15.9 mg/l |
| 15 Jul 2024, 10:31 | 1.89 | 1.89 mg/l |
| 27 Jun 2024, 09:59 | 2.19 | 2.19 mg/l |
Phosphate
orthophosphate, reactive, as P · code 0180 · mg/l
0.04 mg/l
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 0.04 | 0.04 mg/l |
| 18 May 2026, 11:06 | 0.014 | 0.014 mg/l |
| 7 May 2026, 12:35 | 0.019 | 0.019 mg/l |
| 27 Apr 2026, 12:40 | 0.013 | 0.013 mg/l |
| 5 Mar 2026, 12:25 | 0.02 | 0.02 mg/l |
| 19 Feb 2026, 10:33 | 0.031 | 0.031 mg/l |
| 2 Jan 2026, 14:17 | 0.025 | 0.025 mg/l |
| 12 Dec 2025, 11:30 | 0.039 | 0.039 mg/l |
| 12 Nov 2025, 14:15 | 0.056 | 0.056 mg/l |
| 8 Aug 2025, 10:24 | 0.05 | 0.05 mg/l |
| 7 Jul 2025, 15:13 | 0.043 | 0.043 mg/l |
| 3 Jun 2025, 11:38 | 0.023 | 0.023 mg/l |
| 10 Apr 2025, 13:16 | <0.01 | below 0.01 mg/l (not detected above this) |
| 6 Mar 2025, 10:53 | <0.01 | below 0.01 mg/l (not detected above this) |
| 12 Feb 2025, 12:59 | <0.01 | below 0.01 mg/l (not detected above this) |
| 28 Jan 2025, 12:48 | 0.024 | 0.024 mg/l |
| 10 Dec 2024, 10:13 | 0.033 | 0.033 mg/l |
| 25 Nov 2024, 11:34 | 0.09 | 0.09 mg/l |
| 15 Oct 2024, 13:40 | 0.021 | 0.021 mg/l |
| 27 Sep 2024, 10:31 | 0.069 | 0.069 mg/l |
| 15 Jul 2024, 10:31 | 0.021 | 0.021 mg/l |
| 27 Jun 2024, 09:59 | 0.018 | 0.018 mg/l |
Conductivity
at 25 °C · code 0077 · µS/cm
777 µS/cm
Sampled 29 May 2026, 4 months ago · 22 results banked
Every result (22)
| Sampled | Result as published | Reads as |
|---|---|---|
| 29 May 2026, 10:09 | 777 | 777 µS/cm |
| 18 May 2026, 11:06 | 749 | 749 µS/cm |
| 7 May 2026, 12:35 | 761 | 761 µS/cm |
| 27 Apr 2026, 12:40 | 770 | 770 µS/cm |
| 5 Mar 2026, 12:25 | 745 | 745 µS/cm |
| 19 Feb 2026, 10:33 | 730 | 730 µS/cm |
| 2 Jan 2026, 14:17 | 794 | 794 µS/cm |
| 12 Dec 2025, 11:30 | 850 | 850 µS/cm |
| 12 Nov 2025, 14:15 | 726 | 726 µS/cm |
| 8 Aug 2025, 10:24 | 699 | 699 µS/cm |
| 7 Jul 2025, 15:13 | 695 | 695 µS/cm |
| 3 Jun 2025, 11:38 | 763 | 763 µS/cm |
| 10 Apr 2025, 13:16 | 787 | 787 µS/cm |
| 6 Mar 2025, 10:53 | 804 | 804 µS/cm |
| 12 Feb 2025, 12:59 | 748 | 748 µS/cm |
| 28 Jan 2025, 12:48 | 791 | 791 µS/cm |
| 10 Dec 2024, 10:13 | 741 | 741 µS/cm |
| 25 Nov 2024, 11:34 | 707 | 707 µS/cm |
| 15 Oct 2024, 13:40 | 783 | 783 µS/cm |
| 27 Sep 2024, 10:31 | 821 | 821 µS/cm |
| 15 Jul 2024, 10:31 | 810 | 810 µS/cm |
| 27 Jun 2024, 09:59 | 803 | 803 µS/cm |
Everything measured here
76 determinands, each kept by its code, unit and sample material: results in different units or on different materials are never mixed. A “below” result is under the laboratory's detection limit, not zero.
Show all 76 rows
| Determinand | Material | Results | First – last | Latest result |
|---|---|---|---|---|
| Oxygen, Dissolved, % Saturation 9901 | River water | 22 | Jun 2024 – May 2026 | 87.2% 29 May 2026 |
| Oxygen, Dissolved as O2 9924 | River water | 22 | Jun 2024 – May 2026 | 8.64 mg/l 29 May 2026 |
| Temperature of Water 0076 | River water | 22 | Jun 2024 – May 2026 | 15.7 °C 29 May 2026 |
| pH 0061 | River water | 22 | Jun 2024 – May 2026 | 8.14 29 May 2026 |
| Ammoniacal Nitrogen as N 0111 | River water | 22 | Jun 2024 – May 2026 | 0.062 mg/l 29 May 2026 |
| Nitrate as N 0117 | River water | 22 | Jun 2024 – May 2026 | 0.732 mg/l 29 May 2026 |
| Orthophosphate, reactive as P 0180 | River water | 22 | Jun 2024 – May 2026 | 0.04 mg/l 29 May 2026 |
| Conductivity at 25 C 0077 | River water | 22 | Jun 2024 – May 2026 | 777 µS/cm 29 May 2026 |
| 10:2 Fluorotelomer sulfonic acid 2994 | River water | 1 | Feb 2026 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (F-53B Minor) 2993 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 2-(N-Ethylperfluorooctanesulfonamido)acetic acid (B) 2942 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 2-(N-Ethylperfluorooctanesulfonamido)acetic acid (L) 2991 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 2-(N-Methylperfluorooctanesulfonamido)acetic acid (B) 2943 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 2-(N-Methylperfluorooctanesulfonamido)acetic acid (L) 2990 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 2H,2H,3H,3H-Perfluorooctanoic acid 2989 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 2H-Perfluoro-2-decenoic acid 2888 | River water | 1 | Feb 2026 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 3-Perfluoroheptylpropanoic acid 2925 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 3:3 Fluorotelomer carboxylic acid 2926 | River water | 2 | Aug 2025 – Feb 2026 | below 0.004 µg/l 19 Feb 2026 |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) 2988 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 4:2 Fluorotelomer sulfonic acid 2987 | River water | 1 | Feb 2026 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 5:1:2 Fluorotelomer betaine 2887 | River water | 1 | Feb 2026 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 5:3 Fluorotelomer betaine 2886 | River water | 1 | Feb 2026 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| 6:2 Fluorotelomer phosphate diester 2986 | River water | 1 | Feb 2026 – Feb 2026 | below 0.004 µg/l 19 Feb 2026 |
| 6:2 Fluorotelomer sulfonamide amine oxide (6:2 FTNO) (Capstone A) 2841 | River water | 1 | Feb 2026 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 6:2 Fluorotelomer sulfonamide betaine 2985 | River water | 1 | Feb 2026 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 6:2 Fluorotelomer sulfonic acid 2984 | River water | 2 | Aug 2025 – Feb 2026 | 0.032 µg/l 19 Feb 2026 |
| 6:2/8:2 Fluorotelomer phosphate diester 2884 | River water | 1 | Feb 2026 – Feb 2026 | below 0.01 µg/l 19 Feb 2026 |
| 6:6 Perfluorophosphinic acid 2883 | River water | 1 | Feb 2026 – Feb 2026 | below 0.004 µg/l 19 Feb 2026 |
| 6:8 Perfluorophosphinic acid 2882 | River water | 1 | Feb 2026 – Feb 2026 | below 0.01 µg/l 19 Feb 2026 |
| 8:2 Fluorotelomer phosphate diester 2880 | River water | 1 | Feb 2026 – Feb 2026 | below 0.004 µg/l 19 Feb 2026 |
| 8:2 Fluorotelomer sulfonic acid 2983 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| 8:8 Perfluorophosphinic acid 2879 | River water | 1 | Feb 2026 – Feb 2026 | below 0.01 µg/l 19 Feb 2026 |
| 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid 2982 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Alkalinity to pH 4.5 as CaCO3 0162 | River water | 22 | Jun 2024 – May 2026 | 260 mg/l 29 May 2026 |
| Ammonia un-ionised as N 0119 | River water | 22 | Jun 2024 – May 2026 | 0.00171 mg/l 29 May 2026 |
| BOD : 5 Day ATU 0085 | River water | 21 | Jun 2024 – May 2026 | 1.1 mg/l 29 May 2026 |
| Hexafluoropropylene oxide dimer acid (Gen X) 2981 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Hexafluoropropylene oxide trimer acid 2980 | River water | 1 | Feb 2026 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| N-Ethylperfluorooctanesulfonamide 2977 | River water | 2 | Aug 2025 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| N-methylperfluorooctanesulfonamide 2975 | River water | 2 | Aug 2025 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| Nitrite as N 0118 | River water | 22 | Jun 2024 – May 2026 | 0.0083 mg/l 29 May 2026 |
| Nitrogen, Total Oxidised as N 0116 | River water | 22 | Jun 2024 – May 2026 | 0.74 mg/l 29 May 2026 |
| No flow /No sample 7668 | River water | 5 | Aug 2024 – Jun 2026 | No flow/discharge at sampling point 29 Jun 2026 |
| Perfluoro(2-ethoxyethane)sulfonic acid 2924 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoro(4-methoxybutanoic) acid 2923 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoro-3,6-dioxaheptanoic acid 2922 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoro-3-methoxypropanoic acid 2921 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoro-4-ethylcyclohexanesulfonic acid 2973 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorobutanesulfonic acid 2972 | River water | 2 | Aug 2025 – Feb 2026 | 0.007 µg/l 19 Feb 2026 |
| Perfluorobutanoic acid 2995 | River water | 2 | Aug 2025 – Feb 2026 | 0.0011 µg/l 19 Feb 2026 |
| Perfluorobutylsulfonamide (perfluorobutane sulfonamide) 2970 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorodecanesulfonic acid 2969 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorodecanoic acid 8892 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorododecane sulfonic acid 2968 | River water | 2 | Aug 2025 – Feb 2026 | below 0.005 µg/l 19 Feb 2026 |
| Perfluorododecanoic acid 8894 | River water | 2 | Aug 2025 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| Perfluoroheptanesulfonic acid 2967 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoroheptanoic acid 8889 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorohexane sulfonamido amine 2874 | River water | 1 | Feb 2026 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorohexanesulfonamide 2965 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorohexanesulfonic acid (B) 2944 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorohexanesulfonic acid (L) 2964 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorohexanoic acid 8888 | River water | 2 | Aug 2025 – Feb 2026 | 0.0014 µg/l 19 Feb 2026 |
| Perfluorononanesulfonic acid 2963 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorononanoic acid 8891 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorooctadecanoic acid 2962 | River water | 2 | Aug 2025 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| Perfluorooctanesulfonamide 2961 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorooctanesulfonic acid (branched) 2960 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorooctanesulfonic acid (linear) 2959 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluorooctanesulfonic acid (total) 2958 | River water | 1 | Feb 2026 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
| Perfluorooctanoic acid 8890 | River water | 2 | Aug 2025 – Feb 2026 | 0.00068 µg/l 19 Feb 2026 |
| Perfluoropentanesulfonic acid 2957 | River water | 2 | Aug 2025 – Feb 2026 | below 0.0005 µg/l 19 Feb 2026 |
| Perfluoropentanoic acid 8887 | River water | 2 | Aug 2025 – Feb 2026 | 0.0011 µg/l 19 Feb 2026 |
| Perfluorotetradecanoic acid 8895 | River water | 2 | Aug 2025 – Feb 2026 | below 0.006 µg/l 19 Feb 2026 |
| Perfluorotridecanoic acid 2955 | River water | 2 | Aug 2025 – Feb 2026 | below 0.002 µg/l 19 Feb 2026 |
| Perfluoroundecane sulfonic acid 2953 | River water | 2 | Aug 2025 – Feb 2026 | below 0.004 µg/l 19 Feb 2026 |
| Perfluoroundecanoic acid 8893 | River water | 2 | Aug 2025 – Feb 2026 | below 0.001 µg/l 19 Feb 2026 |
FloodRadar does not grade these results: there is no overall score, and official river classifications are a separate dataset. A sample taken downstream of an overflow does not by itself show where anything in it came from. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels.
Water samples: Environment Agency Water Quality Archive, © Environment Agency and/or database right 2026, Open Government Licence v3.0.
Contains OS data © Crown copyright and database rights 2026.