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tapwater
England and Wales average 9.0

Tap water in DL3, DarlingtonSafe to drink.Slightly hard.

Supplied by Northumbrian Water. 4,719 samples, 20 substances, latest on 18 December 2025. Everything is inside the legal limit, and nothing comes close to it.

See the filter we recommendSee everything that was tested

9.7 / 10

The tank is as full as the score. The specks are the minerals that make water hard.

What to do about it

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High-volume under-sink filtration without RO complexity

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Basic chlorine and taste improvement on a budget

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What's in a glass of DL3 water

Every bubble is a substance the lab measured. The higher it floats, the closer it came to its legal limit, the dashed line at the top.

Aluminium came closest to a limit, at 9% of it. 18 of 18 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitCadmium: 0.000018 mg/L, <1% of the 0.005 mg/L limitCadmium<1%Lead: 0.000065 mg/L, <1% of the 0.01 mg/L limitLead<1%Arsenic: 0.000081 mg/L, <1% of the 0.01 mg/L limitArsenic<1%Boron: 0.0093 mg/L, <1% of the 1 mg/L limitBoron<1%Manganese: 0.00056 mg/L, 1% of the 0.05 mg/L limitManganese1%Nitrite: 0.0061 mg/L, 1% of the 0.5 mg/L limitNitrite1%Chromium: 0.00067 mg/L, 1% of the 0.05 mg/L limitChromium1%Copper: 0.027 mg/L, 1% of the 2 mg/L limitCopper1%Selenium: 0.00083 mg/L, 2% of the 0.04 mg/L limitSelenium2%Fluoride: 0.038 mg/L, 3% of the 1.5 mg/L limitFluoride3%Nitrate: 1.5 mg/L, 3% of the 50 mg/L limitNitrate3%Antimony: 0.00016 mg/L, 3% of the 0.005 mg/L limitAntimony3%Bromate: 0.0005 mg/L, 5% of the 0.01 mg/L limitBromate5%Turbidity: 0.24 NTU, 6% of the 4 NTU limitTurbidity6%Nickel: 0.0012 mg/L, 6% of the 0.02 mg/L limitNickel6%Colour: 1.3 mg/L Pt/Co, 7% of the 20 mg/L Pt/Co limitColour7%Iron: 0.018 mg/L, 9% of the 0.2 mg/L limitIron9%Aluminium: 0.019 mg/L, 9% of the 0.2 mg/L limitAluminium9%
  1. Aluminium9%
  2. Iron9%
  3. Colour7%
  4. Turbidity6%
  5. Nickel6%
  6. Bromate5%
  7. Antimony3%
  8. Nitrate3%
  9. Fluoride3%
  10. Selenium2%
  11. Copper1%
  12. Chromium1%
  13. Nitrite1%
  14. Manganese1%
  15. Boron<1%
  16. Arsenic<1%
  17. Lead<1%
  18. Cadmium<1%
  • Conductivity 240 µS/cm
  • pH 7.9 pH
All 20 results as a table
SubstanceResultLegal limitShare of limit
Iron0.018 mg/L0.2 mg/L
9%
Aluminium0.019 mg/L0.2 mg/L
9%
Colour1.3 mg/L Pt/Co20 mg/L Pt/Co
7%
Manganese0.00056 mg/L0.05 mg/L
1%
Turbidity0.24 NTU4 NTU
6%
Conductivity240 µS/cmNo legal limit–
pH7.9 pHNo legal limit–
Nitrite0.0061 mg/L0.5 mg/L
1%
Copper0.027 mg/L2 mg/L
1%
Boron0.0093 mg/L1 mg/L
<1%
Arsenic0.000081 mg/L0.01 mg/L
<1%
Antimony0.00016 mg/L0.005 mg/L
3%
Chromium0.00067 mg/L0.05 mg/L
1%
Nickel0.0012 mg/L0.02 mg/L
6%
Nitrate1.5 mg/L50 mg/L
3%
Lead0.000065 mg/L0.01 mg/L
<1%
Fluoride0.038 mg/L1.5 mg/L
3%
Selenium0.00083 mg/L0.04 mg/L
2%
Bromate0.0005 mg/L0.01 mg/L
5%
Cadmium0.000018 mg/L0.005 mg/L
<1%

168mg of limescale minerals in every litre

Middling hardness. Some scale, slowly

Below the point where a softener pays for itself. Descaling the kettle now and then is all most homes need.

Soft400 mg/L
Outside your tap

Your river is the Skerne from Demons Beck to Tees, rated poor

The Environment Agency rated the Skerne from Demons Beck to Tees as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by fish, water plants and algae and phosphate. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants. Its ecological rating has dropped since the previous assessment.

None of this is a test of your tap water. Environment Agency record · River health across England

DL3 in short

Tap water in DL3 (Darlington) is supplied by Northumbrian Water in the Darlington Central zone and scores 9.7 out of 10, against an England and Wales average of 9.0. None of the 20 tested substances came close to a limit. The latest sample is from 18 December 2025.

  • 2nd cleanest of 3 areas tested in DarlingtonSquarely mid-table for Darlington, between DL2 on 9.7 and DL1 on 9.6.
  • 0.7 points above the national average of 9Cleaner than the typical tested district in the UK. Compare every area
  • Nothing tested came within 40% of its legal limitThe highest was Aluminium at 9% of the 0.2 mg/L maximum. See every reading

Next door

DL29.7 out of 10 · 168 mg/LDL19.6 out of 10 · 168 mg/L

Questions about DL3 water

Is DL3 tap water safe to drink?

Based on the latest tests, DL3 (Darlington) water scores 9.7/10, which is safe. 0 of 20 tested contaminants exceeded recommended levels. Water is supplied by Northumbrian Water.

What contaminants are in DL3 water?

We tested 20 contaminants in DL3 water. None exceeded recommended safe levels.

Who supplies water in DL3?

DL3 (Darlington) is supplied by Northumbrian Water. You can view their full profile and compliance data on our supplier page.

Is DL3 water hard or soft?

Water in DL3 (Darlington) has a hardness of 168 mg/L CaCO3, which is classified as moderately hard. This is a moderate hardness level.

Should I use a water filter in DL3?

DL3 water scored 9.7/10 with no contaminants above recommended levels. A filter is optional but can improve taste, especially if you notice a chlorine flavour. See our filter recommendations for your area.

Are there PFAS forever chemicals in DL3 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for DL3, and the Environment Agency has no PFAS detections in rivers or groundwater within 10 km of it. That reflects where sampling has happened as much as the water itself.

How clean is the river near DL3?

The Environment Agency rated the Skerne from Demons Beck to Tees as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by fish, water plants and algae and phosphate. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants. Its ecological rating has dropped since the previous assessment. This is a rating of the river, not of tap water in DL3, which is treated before it reaches homes.

Keep reading

How to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map

River and groundwater readings near DL3

Environment Agency samples from rivers, groundwater and reservoirs nearby. Not your tap water. For scale they are shown against drinking water limits; rivers are judged against much stricter environmental standards, and on those every river in England fails for chemicals.

SubstanceReadingDrinking water limit
Iron0.18 mg/L0.2 mg/L
pH8.54 pHNone
Temperature16.1 °CNone
Conductivity151 µS/cmNone
Ammonia0.0038 mg/L0.5 mg/L
Nitrate0.14 mg/L50 mg/L
Nitrite0.0025 mg/L0.5 mg/L
Phosphate0.016 mg/LNone
Dissolved Oxygen10.8 mg/LNone
Lead0.0038 mg/L0.01 mg/L
Cadmium0.000011 mg/L0.005 mg/L
Zinc0.0034 mg/LNone
Nickel0.00078 mg/L0.02 mg/L
Turbidity2.8 NTU4 NTU
Copper0.0009 mg/L2 mg/L
Manganese0.02 mg/L0.05 mg/L

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Source: Northumbrian Water test results, published through the Stream Water Data Portal; rivers and PFAS from the Environment Agency. Page updated . How we score · Where the data comes from