HP5 tap water: what's in it?
Affinity Water: at least 20 tests failed UK drinking-water standards in 2025 (DWI, company-wide).
Some published DWI figures don't reconcile or identify a company, so we've left them out; the true number may be higher. England overall: 99.97% of tests met standards.
HP5 tap water quality report · 2026
Hardness
Not covered
We do not have a verified hardness figure for this area. Ask your water company for its water quality report.
Details
We do not have a verified hardness figure for this area. Ask your water company for its water quality report.
Hosepipe ban
In force in part of Affinity Water's area
A ban has been reported, but the notice doesn't confirm which parts of the supply area it covers. Check with your water company before using a hosepipe. Checked 11 October 2026 at 02:34
Details
A ban has been reported, but the notice doesn't confirm which parts of the supply area it covers. Check with your water company before using a hosepipe. Checked 11 October 2026 at 02:34
Storm overflows
4 overflows within 10 km of HP5 centre
55 spills in 2025
Details
55 spills in 2025
Lead pipes
69% built before 1973
Estimate, not a test. Homes in the parts of HP5 we can match to council-tax records (100% of its postcodes) whose build period is known; the share with no recorded build period isn't published for these areas. Allowing for suppressed counts: 67–69%. England and Wales: 61% (2026).
Details
Estimate, not a test. Homes in the parts of HP5 we can match to council-tax records (100% of its postcodes) whose build period is known; the share with no recorded build period isn't published for these areas. Allowing for suppressed counts: 67–69%. England and Wales: 61% (2026).
Who supplies water in HP5
Supplies 720 of 730 postcodes (99%)
Affinity Water's phone number isn't in our records; their contact page lists it.
We can't tell your sewerage company from official data for this area. It's named on your water bill.
Also supplied here: Thames Water (6 of 730 postcodes (1%))
Boundary or unplaced: 4 postcodes
Drinking-water test record
Affinity Water: 720 of 730 postcodes
Affinity Water
Affinity Water, company-wide
- Regulator
- DWI
- Report year
- 2025
- Failed tests
- Not shown
- Tests
- 189,963
The regulator's published total and its company rows disagree, so we don't show a count.
| Parameter | Failed tests |
|---|---|
| E. coli (confirmed) | Failed tests: 4 |
| Enterococci (confirmed) | Failed tests: 2 |
| Iron | Failed tests: 1 |
| Lead | Failed tests: 6 |
| Nickel | Failed tests: 3 |
| Total coliforms (confirmed) | Failed tests: 4 |
Source: DWI england 2025, Annex B — dated 6 July 2026, read 13 October 2026
Source: DWI england 2025, Annex A — dated 6 July 2026, read 13 October 2026
England: 99.97% of tests met standards in 2025 (DWI).
Source: DWI england 2025, national compliance — dated 6 July 2026, read 13 October 2026
Thames Water: 6 of 730 postcodes
Thames Water
Thames Water, company-wide
- Regulator
- DWI
- Report year
- 2025
- Failed tests
- Not shown
- Tests
- 436,206
The regulator's published total and its company rows disagree, so we don't show a count.
| Parameter | Failed tests |
|---|---|
| E. coli (confirmed) | Failed tests: 8 |
| Iron | Failed tests: 6 |
| Lead | Failed tests: 13 |
| Nickel | Failed tests: 20 |
| Nitrite – consumers taps | Failed tests: 4 |
| Total coliforms (confirmed) | Failed tests: 13 |
| Turbidity – indicator | Failed tests: 4 |
Source: DWI england 2025, Annex B — dated 6 July 2026, read 13 October 2026
Source: DWI england 2025, Annex A — dated 6 July 2026, read 13 October 2026
England: 99.97% of tests met standards in 2025 (DWI).
Source: DWI england 2025, national compliance — dated 6 July 2026, read 13 October 2026
How hard is the water in HP5?
Across HP5's supply zones, hardness ranges from 282 mg/l (hard) to 288 mg/l (hard). Those 3 zones cover 7% of its postcodes.
3 identified supply zones in HP5
Beaconsfield/Chalfont St Giles · Affinity Water (48 of 730 postcodes)
288 mg/l · 20.2 °Clark · 16.1 °dH · 28.8 °fH
Zone average.
Beaconsfield/Chalfont St Giles (supply zone) · 1 January 2025 to 31 December 2025
Source: Affinity Water — dated 1 January 2025 to 31 December 2025, read 29 September 2026
Berkhamsted · Affinity Water (4 of 730 postcodes)
286 mg/l · 20.1 °Clark · 16.0 °dH · 28.6 °fH
From the company's postcode lookup.
Berkhamsted (supply zone) · read on 28 September 2026
Source: Affinity Water — read 28 September 2026
Rickmansworth/Gerrards Cross · Affinity Water (2 of 730 postcodes)
282 mg/l · 19.8 °Clark · 15.8 °dH · 28.2 °fH
From the company's postcode lookup.
Rickmansworth/Gerrards Cross (supply zone) · read on 29 September 2026
Source: Affinity Water — read 29 September 2026
672 postcodes without an identified supply zone
Affinity Water (666 of 730 postcodes)
We do not have a verified hardness figure for this area. Ask your water company for its water quality report.
Thames Water (6 of 730 postcodes)
“all the water in our region is hard”
Thames Water, company-wide · read on 26 September 2026
Source: Thames Water — dated 26 September 2026, read 26 September 2026
Storm overflows nearby
4 overflows within 10 km of HP5 centre · 55 spills in 2025
HP5 (district) · 2025
Source: Environment Agency EDM annual return 2025 — dated 20 August 2026, read 13 October 2026
Overflows here are run by Thames Water.
2 of these were monitored for only part of 2025.
Nearest 4 shown
CHESHAM WASTEWATER TREATMENT WORKS
Into THE RIVER CHESS · 3.5 km from the centre of HP5
7 spills · 57.8 hours · Monitored 100% of 2025
Amersham Balancing Tanks
Into Misbourne · 6.6 km from the centre of HP5
13 spills · 167 hours · Monitored 99.6% of 2025
BERKHAMSTED SEWAGE TREATMENT WORKS
Into THE GRAND UNION CANAL · 6.7 km from the centre of HP5
35 spills · 209.8 hours · Monitored 100% of 2025
Trumps Green
Into River Bulborne · 7.6 km from the centre of HP5
0 spills · 0 hours · Monitored 99.7% of 2025
Annual 2025 figures from monitored overflows. Not live, and not a bathing-water or tap-water verdict.
- 57 England outfalls in the 2025 return had no usable location and aren't counted.
- Northern Ireland isn't covered: No licensed annual per-outfall source in the approved source list; BT postcode coordinates require an LPS licence.
Older homes and lead pipes
69% built before 1973
69% of homes here were built before 1973 — estimate, not a test.
Homes in the parts of HP5 we can match to council-tax records (100% of its postcodes) whose build period is known; the share with no recorded build period isn't published for these areas. Allowing for suppressed counts: 67–69%. England and Wales: 61% (2026).
Older homes are more likely to have lead pipes. Only a test tells you whether yours does.
HP5 (district) · 2026
Source: Valuation Office Agency, Council Tax: stock of properties — dated 31 March 2026, read 24 September 2026
Fluoride
We cannot confirm whether this area is part of a water fluoridation scheme. Ask your water supplier using your postcode.
Around one in ten people in England receive drinking water supplied by a fluoridation scheme.
England · 2026 health monitoring report
Source: UKHSA and DHSC — dated 30 March 2026, read 13 October 2026
Hosepipe bans
What you can do
General picks — we don't hold your hardness
As an Amazon Associate we earn from qualifying purchases. Links go to amazon.com; Amazon's Earn Globally service can localise them to amazon.co.uk. Check the model and UK delivery before buying.
Water filter jugs
LifeStraw
LSH7GLSPK21
Performance certification:
Certified by WQA to NSF/ANSI 42 for Aesthetic Chlorine and Taste and Odor; Certified by WQA to NSF/ANSI 53 for Lead and Mercury; Certified by WQA to NSF/ANSI 401 for Microplastics (a US/international standard; it is not UK approval)
View Detailsreduces chlorine taste and odour in drinking water.
A UK retailer lists this model. Amazon UK stock and delivery are unverified; this Amazon link may not ship to the UK. Check the exact model and UK delivery before you pay.
UK availability evidence checked 14 October 2026.
Shower filters
Weddell Water
WD-100BL
Performance certification:
Certified by NSF to NSF/ANSI 177 for Free Available Chlorine Reduction (a US/international standard; it is not UK approval)
View Detailsreduces chlorine in shower water; does not soften water.
A UK retailer lists this model. Amazon UK stock and delivery are unverified; this Amazon link may not ship to the UK. Check the exact model and UK delivery before you pay.
Check it fits your shower fitting before buying; a US fitting may need an adaptor.
UK availability evidence checked 14 October 2026.
We haven't verified a lead test kit for UK buyers yet.
What a pick has to pass:
- A lead result reported by a laboratory accredited for that test (UKAS, ISO/IEC 17025), named on the kit's listing
- UK availability evidenced by Amazon UK, the manufacturer or a UK retailer, checked in the last 90 days
Start with your water company: if you think you have lead pipes, you can ask it to test the water at your kitchen tap. Which water test you need
Common water problems
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Water softener cost UK 2026: price by home size
Why is my tap water cloudy or white?
Why is my tap water cloudy or white? (UK)
Brown tap water: causes and what to do (UK)
Why does my tap water taste metallic?
Tap water tastes metallic? Causes and fixes (UK)
Questions about tap water in HP5
- Is the water in HP5 hard or soft?
- Affinity Water: We do not have a verified hardness figure for this area. Ask your water company for its water quality report. Affinity Water: hard, 288 mg/l, 20.2 °Clark, 16.1 °dH, 28.8 °fH (Beaconsfield/Chalfont St Giles (supply zone), 1 January 2025 to 31 December 2025). Zone average. Thames Water: “all the water in our region is hard” (Thames Water, Thames Water, company-wide, read on 26 September 2026). Affinity Water: hard, 286 mg/l, 20.1 °Clark, 16.0 °dH, 28.6 °fH (Berkhamsted (supply zone), read on 28 September 2026). From the company's postcode lookup. Affinity Water: hard, 282 mg/l, 19.8 °Clark, 15.8 °dH, 28.2 °fH (Rickmansworth/Gerrards Cross (supply zone), read on 29 September 2026). From the company's postcode lookup.
- What does the drinking water regulator's record show for HP5?
- Affinity Water: at least 20 tests failed UK drinking-water standards in 2025 (DWI, company-wide). Some published DWI figures don't reconcile or identify a company, so we've left them out; the true number may be higher. England overall: 99.97% of tests met standards.
- Could homes in HP5 have lead pipes?
- 69% of homes here were built before 1973 — estimate, not a test. Homes in the parts of HP5 we can match to council-tax records (100% of its postcodes) whose build period is known; the share with no recorded build period isn't published for these areas. Allowing for suppressed counts: 67–69%. England and Wales: 61% (2026). Older homes are more likely to have lead pipes. Only a test tells you whether yours does.
- Is the water in HP5 fluoridated?
- We cannot confirm whether this area is part of a water fluoridation scheme. Ask your water supplier using your postcode. Around one in ten people in England receive drinking water supplied by a fluoridation scheme.
Sources and method
- Water Company Boundaries (UC2) ↗ · 19 September 2026 · read 20 September 2026
- DWI england 2025, Annex B ↗ · 2025 · read 13 October 2026
- DWI england 2025, national compliance ↗ · 2025 · read 13 October 2026
- Affinity Water ↗ · 1 January 2025 to 31 December 2025 · read 29 September 2026
- Thames Water ↗ · read on 26 September 2026 · read 26 September 2026
- Affinity Water ↗ · read on 28 September 2026 · read 28 September 2026
- Affinity Water ↗ · read on 29 September 2026 · read 29 September 2026
- Environment Agency EDM annual return 2025 ↗ · 2025 · read 13 October 2026
- Valuation Office Agency, Council Tax: stock of properties ↗ · 2026 · read 24 September 2026
- UKHSA and DHSC ↗ · 2026 health monitoring report · read 13 October 2026
- Environment Agency ↗ · 11 October 2026 · read 11 October 2026
Affinity Water, Thames Water, Affinity Water, Affinity Water: Database right, used under the publisher's terms.
Water company boundaries © Water UK, licensed under CC BY 4.0Contains public sector information licensed under the Open Government Licence v3.0All content is available under the Open Government Licence v3.0, except where otherwise stated © Crown copyright
Data generation uk-2026-10-16-derive6