DL1 tap water: what's in it?
Northumbrian, Essex and Suffolk Water group (figures include Northumbrian Water): at least 36 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.
DL1 tap water quality report · 2026
Hardness
Slightly hard
Darlington Zone (supply zone) · January 2025 to December 2025
Details
Darlington Zone (supply zone) · January 2025 to December 2025
Hosepipe ban
No hosepipe ban
Checked 11 October 2026 at 02:34
Details
Checked 11 October 2026 at 02:34
Storm overflows
56 overflows within 10 km of DL1 centre
669 spills in 2025
Details
669 spills in 2025
Lead pipes
61% built before 1973
Estimate, not a test. Homes in the parts of DL1 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: 60–61%. England and Wales: 61% (2026).
Details
Estimate, not a test. Homes in the parts of DL1 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: 60–61%. England and Wales: 61% (2026).
Who supplies water in DL1
Part of Northumbrian, Essex and Suffolk Water
Supplies 1,412 of 1,412 postcodes (100%)
Sewerage: Usually Northumbrian Water — they provide water and sewerage across most of their area. Your water bill confirms yours.
Drinking-water test record
Northumbrian Water: 1,412 of 1,412 postcodes
Northumbrian Water
Northumbrian, Essex and Suffolk Water group, includes Northumbrian Water
- Regulator
- DWI
- Report year
- 2025
- Failed tests
- Not shown
- Tests
- 266,202
The regulator's published total and its company rows disagree, so we don't show a count.
| Parameter | Failed tests |
|---|---|
| Aluminium | Failed tests: 4 |
| E. coli (confirmed) | Failed tests: 3 |
| Enterococci (confirmed) | Failed tests: 1 |
| Iron | Failed tests: 9 |
| Lead | Failed tests: 5 |
| Manganese | Failed tests: 3 |
| Nickel | Failed tests: 2 |
| Nitrite – consumers taps | Failed tests: 1 |
| Sodium | Failed tests: 1 |
| Total coliforms (confirmed) | Failed tests: 7 |
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 DL1?
72% of DL1's postcodes are in the Darlington Zone supply zone (Northumbrian Water): 148 mg/l, slightly hard.
Darlington Zone · Northumbrian Water (1,016 of 1,412 postcodes)
148 mg/l · 10.4 °Clark · 8.3 °dH · 14.8 °fH
Zone average.
Darlington Zone (supply zone) · January 2025 to December 2025
Source: Northumbrian Water — dated January 2025 to December 2025, read 28 September 2026
4 identified supply zones in DL1
Darlington Zone · Northumbrian Water (1,016 of 1,412 postcodes)
148 mg/l · 10.4 °Clark · 8.3 °dH · 14.8 °fH
Zone average.
Darlington Zone (supply zone) · January 2025 to December 2025
Source: Northumbrian Water — dated January 2025 to December 2025, read 28 September 2026
Lartington WTW to Longnewton Zone · Northumbrian Water (274 of 1,412 postcodes)
77 mg/l · 5.4 °Clark · 4.3 °dH · 7.7 °fH
Zone average.
Lartington WTW to Longnewton Zone (supply zone) · January 2025 to December 2025
Source: Northumbrian Water — dated January 2025 to December 2025, read 28 September 2026
Sadberge Zone · Northumbrian Water (88 of 1,412 postcodes)
128 mg/l · 9.0 °Clark · 7.2 °dH · 12.8 °fH
Zone average.
Sadberge Zone (supply zone) · January 2025 to December 2025
Source: Northumbrian Water — dated January 2025 to December 2025, read 28 September 2026
Sedgefield & Aycliffe Zone · Northumbrian Water (13 of 1,412 postcodes)
81 mg/l · 5.7 °Clark · 4.6 °dH · 8.1 °fH
Zone average.
Sedgefield & Aycliffe Zone (supply zone) · January 2025 to December 2025
Source: Northumbrian Water — dated January 2025 to December 2025, read 28 September 2026
21 postcodes without an identified supply zone
Northumbrian Water (21 of 1,412 postcodes)
We do not have a verified hardness figure for this area. Ask your water company for its water quality report.
Storm overflows nearby
56 overflows within 10 km of DL1 centre · 669 spills in 2025
DL1 (district) · 2025
Source: Environment Agency EDM annual return 2025 — dated 20 August 2026, read 13 October 2026
Overflows here are run by Northumbrian Water.
54 of these were monitored for only part of 2025.
Nearest 5 shown
EASSON ROAD/DODDS STREET CSO
Into RIVER SKERNE · 0.8 km from the centre of DL1
3 spills · 0.6 hours · Monitored 98.8% of 2025
FORSTER STREET/EASSON ROAD CSO
Into RIVER SKERNE · 0.8 km from the centre of DL1
0 spills · 0 hours · Monitored 96.1% of 2025
REAR FORSTER ST/EASSON ROAD CSO
Into RIVER SKERNE · 0.8 km from the centre of DL1
2 spills · 0.6 hours · Monitored 89% of 2025
GLADSTONE STREET (G1)
Into SKERNE · 0.8 km from the centre of DL1
5 spills · 1.3 hours · Monitored 99.9% of 2025
DARLINGTON CROWN STREET NO 34 CSO
Into RIVER SKERNE · 1 km from the centre of DL1
11 spills · 30 hours · Monitored 100% 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
61% built before 1973
61% of homes here were built before 1973 — estimate, not a test.
Homes in the parts of DL1 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: 60–61%. England and Wales: 61% (2026).
Older homes are more likely to have lead pipes. Only a test tells you whether yours does.
DL1 (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 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 DL1
- Is the water in DL1 hard or soft?
- Northumbrian Water: slightly hard, 148 mg/l, 10.4 °Clark, 8.3 °dH, 14.8 °fH (Darlington Zone (supply zone), January 2025 to December 2025). Zone average. Northumbrian Water: soft, 77 mg/l, 5.4 °Clark, 4.3 °dH, 7.7 °fH (Lartington WTW to Longnewton Zone (supply zone), January 2025 to December 2025). Zone average. Northumbrian Water: slightly hard, 128 mg/l, 9.0 °Clark, 7.2 °dH, 12.8 °fH (Sadberge Zone (supply zone), January 2025 to December 2025). Zone average. Northumbrian Water: We do not have a verified hardness figure for this area. Ask your water company for its water quality report. Northumbrian Water: soft, 81 mg/l, 5.7 °Clark, 4.6 °dH, 8.1 °fH (Sedgefield & Aycliffe Zone (supply zone), January 2025 to December 2025). Zone average.
- What does the drinking water regulator's record show for DL1?
- Northumbrian, Essex and Suffolk Water group (figures include Northumbrian Water): at least 36 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 DL1 have lead pipes?
- 61% of homes here were built before 1973 — estimate, not a test. Homes in the parts of DL1 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: 60–61%. 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 DL1 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
- Northumbrian 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
- Northumbrian Water ↗ · January 2025 to December 2025 · read 28 September 2026
- Northumbrian Water ↗ · January 2025 to December 2025 · read 28 September 2026
- Northumbrian Water ↗ · January 2025 to December 2025 · read 28 September 2026
- Northumbrian Water ↗ · January 2025 to December 2025 · 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
Northumbrian Water contact page, Northumbrian Water, Northumbrian Water, Northumbrian Water, Northumbrian 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
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