CO4 tap water: what's in it?
Anglian Water group (figures include Anglian Water): at least 25 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.
CO4 tap water quality report · 2026
Hardness
At least very hard
Gt Horkesley PWSZ (supply zone) · January 2025 to December 2025
Details
Gt Horkesley PWSZ (supply zone) · January 2025 to December 2025
Hosepipe ban
Hosepipe ban in force
Anglian Water (Environment Agency, 11 October 2026). Checked 11 October 2026 at 02:34
Details
Anglian Water (Environment Agency, 11 October 2026). Checked 11 October 2026 at 02:34
Storm overflows
41 overflows within 10 km of CO4 centre
295 spills in 2025
Details
295 spills in 2025
Lead pipes
34% built before 1973
Estimate, not a test. Homes in the parts of CO4 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: 33–34%. England and Wales: 61% (2026).
Details
Estimate, not a test. Homes in the parts of CO4 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: 33–34%. England and Wales: 61% (2026).
Who supplies water in CO4
Part of Anglian Water
Supplies 1,155 of 1,191 postcodes (97%)
We can't confirm your sewerage company from official data for this area.
Also supplied here: Affinity Water (15 of 1,191 postcodes (1%))
Boundary or unplaced: 21 postcodes
Drinking-water test record
Anglian Water: 1,155 of 1,191 postcodes
Anglian Water
Anglian Water group, includes Anglian Water
- Regulator
- DWI
- Report year
- 2025
- Failed tests
- Not shown
- Tests
- 384,536
The regulator's published total and its company rows disagree, so we don't show a count.
| Parameter | Failed tests |
|---|---|
| Copper | Failed tests: 1 |
| E. coli (confirmed) | Failed tests: 1 |
| Iron | Failed tests: 6 |
| Lead | Failed tests: 2 |
| Nickel | Failed tests: 3 |
| Total coliforms (confirmed) | Failed tests: 10 |
| Turbidity – indicator | Failed tests: 2 |
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
Affinity Water: 15 of 1,191 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
How hard is the water in CO4?
Across CO4's supply zones, hardness ranges from 227 mg/l (hard) to 227 mg/l (hard). Those 1 zones cover 1% of its postcodes.
4 identified supply zones in CO4
Gt Horkesley PWSZ · Anglian Water (630 of 1,191 postcodes)
at least 305 mg/l · at least 21.4 °Clark · at least 17.1 °dH · at least 30.5 °fH
Zone average. At least 305 mg/l (very hard or harder); total hardness is higher.
Gt Horkesley PWSZ (supply zone) · January 2025 to December 2025
Source: Anglian Water — dated January 2025 to December 2025, read 28 September 2026
Lexden PWSZ · Anglian Water (431 of 1,191 postcodes)
at least 330 mg/l · at least 23.2 °Clark · at least 18.5 °dH · at least 33.0 °fH
Zone average. At least 330 mg/l (very hard or harder); total hardness is higher.
Lexden PWSZ (supply zone) · January 2025 to December 2025
Source: Anglian Water — dated January 2025 to December 2025, read 28 September 2026
West Bergholt PWSZ · Anglian Water (43 of 1,191 postcodes)
at least 349 mg/l · at least 24.5 °Clark · at least 19.6 °dH · at least 34.9 °fH
Zone average. At least 349 mg/l (very hard or harder); total hardness is higher.
West Bergholt PWSZ (supply zone) · January 2025 to December 2025
Source: Anglian Water — dated January 2025 to December 2025, read 28 September 2026
Surface Zone · Affinity Water (15 of 1,191 postcodes)
227 mg/l · 15.9 °Clark · 12.7 °dH · 22.7 °fH
From the company's postcode lookup.
Surface Zone (supply zone) · read on 28 September 2026
Source: Affinity Water — read 28 September 2026
51 postcodes without an identified supply zone
Anglian Water (51 of 1,191 postcodes)
We do not have a verified hardness figure for this area. Ask your water company for its water quality report.
Storm overflows nearby
41 overflows within 10 km of CO4 centre · 295 spills in 2025
CO4 (district) · 2025
Source: Environment Agency EDM annual return 2025 — dated 20 August 2026, read 13 October 2026
Overflows here are run by Anglian Water.
30 of these were monitored for only part of 2025.
Nearest 5 shown
SPORTS CENTRE MILL RD.
Into Salary Brook · 1.5 km from the centre of CO4
47 spills · 44.5 hours · Monitored 99.5% of 2025
SPORTS CENTRE MILL RD.
Into Salary Brook · 1.5 km from the centre of CO4
23 spills · 22.3 hours · Monitored 99.2% of 2025
SPORTS CENTRE MILL RD.
Into Salary Brook · 1.5 km from the centre of CO4
2 spills · 2.5 hours · Monitored 100% of 2025
SPORTS CENTRE MILL RD.
Into TENDRING STREAMS · 1.5 km from the centre of CO4
6 spills · 6.3 hours · Monitored 98.9% of 2025
SPORTS CENTRE MILL RD.
Into TENDRING STREAMS · 1.5 km from the centre of CO4
8 spills · 3.5 hours · Monitored 87% 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
34% built before 1973
34% of homes here were built before 1973 — estimate, not a test.
Homes in the parts of CO4 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: 33–34%. England and Wales: 61% (2026).
Older homes are more likely to have lead pipes. Only a test tells you whether yours does.
CO4 (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
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 water softener for UK buyers yet.
What a pick has to pass:
- An exact-model listing from NSF, WQA or IAPMO for the model sold in the UK
- Listed to NSF/ANSI 44, the water softener standard
- The manufacturer's documented feed connection and water-pressure range, so a plumber can check them against UK pipework
- UK availability evidenced by Amazon UK, the manufacturer or a UK retailer, checked in the last 90 days
Until we can recommend one, see what a softener costs to buy, fit and run in the UK. Water softener cost
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
How much does a water softener cost in the UK?
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 CO4
- Is the water in CO4 hard or soft?
- Anglian Water: at least very hard, at least 305 mg/l, at least 21.4 °Clark, at least 17.1 °dH, at least 30.5 °fH (Gt Horkesley PWSZ (supply zone), January 2025 to December 2025). Zone average. At least 305 mg/l (very hard or harder); total hardness is higher. Anglian Water: at least very hard, at least 330 mg/l, at least 23.2 °Clark, at least 18.5 °dH, at least 33.0 °fH (Lexden PWSZ (supply zone), January 2025 to December 2025). Zone average. At least 330 mg/l (very hard or harder); total hardness is higher. Anglian Water: We do not have a verified hardness figure for this area. Ask your water company for its water quality report. Anglian Water: at least very hard, at least 349 mg/l, at least 24.5 °Clark, at least 19.6 °dH, at least 34.9 °fH (West Bergholt PWSZ (supply zone), January 2025 to December 2025). Zone average. At least 349 mg/l (very hard or harder); total hardness is higher. Affinity Water: hard, 227 mg/l, 15.9 °Clark, 12.7 °dH, 22.7 °fH (Surface Zone (supply zone), read on 28 September 2026). From the company's postcode lookup.
- What does the drinking water regulator's record show for CO4?
- Anglian Water group (figures include Anglian Water): at least 25 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 CO4 have lead pipes?
- 34% of homes here were built before 1973 — estimate, not a test. Homes in the parts of CO4 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: 33–34%. 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 CO4 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
- Anglian Water contact page ↗ · 13 October 2026 · read 13 October 2026
- DWI england 2025, Annex B ↗ · 2025 · read 13 October 2026
- DWI england 2025, national compliance ↗ · 2025 · read 13 October 2026
- Anglian Water ↗ · January 2025 to December 2025 · read 28 September 2026
- Affinity Water ↗ · read on 28 September 2026 · read 28 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
Anglian Water contact page, 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