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tapwater
England and Wales average 9.0

Tap water in KT24, GuildfordSafe to drink.Slightly hard.

Supplied by Thames Water. 71 samples, 23 substances, latest on 31 December 2025. Everything is inside the legal limit, and nothing comes close to it.

See the filter we recommendSee everything that was tested

9.4 / 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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What's in a glass of KT24 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.

Nitrite came closest to a limit, at 14% of it. 19 of 19 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitSelenium: 0.0004 mg/L, 1% of the 0.04 mg/L limitSelenium1%Manganese: 0.0007 mg/L, 1% of the 0.05 mg/L limitManganese1%Boron: 0.02 mg/L, 2% of the 1 mg/L limitBoron2%Trihalomethanes: 0.002 mg/L, 2% of the 0.1 mg/L limitTrihalomethanes2%Copper: 0.07 mg/L, 4% of the 2 mg/L limitCopper4%Aluminium: 0.0082 mg/L, 4% of the 0.2 mg/L limitAluminium4%Chromium: 0.0025 mg/L, 5% of the 0.05 mg/L limitChromium5%Antimony: 0.0003 mg/L, 6% of the 0.005 mg/L limitAntimony6%Nitrate: 3.1 mg/L, 6% of the 50 mg/L limitNitrate6%Mercury: 0.00007 mg/L, 7% of the 0.001 mg/L limitMercury7%Arsenic: 0.0007 mg/L, 7% of the 0.01 mg/L limitArsenic7%Iron: 0.015 mg/L, 8% of the 0.2 mg/L limitIron8%Fluoride: 0.12 mg/L, 8% of the 1.5 mg/L limitFluoride8%Cadmium: 0.0004 mg/L, 8% of the 0.005 mg/L limitCadmium8%Colour: 1.8 mg/L Pt/Co, 9% of the 20 mg/L Pt/Co limitColour9%Bromate: 0.001 mg/L, 10% of the 0.01 mg/L limitBromate10%Nickel: 0.0024 mg/L, 12% of the 0.02 mg/L limitNickel12%Lead: 0.0013 mg/L, 13% of the 0.01 mg/L limitLead13%Nitrite: 0.07 mg/L, 14% of the 0.5 mg/L limitNitrite14%
  1. Nitrite14%
  2. Lead13%
  3. Nickel12%
  4. Bromate10%
  5. Colour9%
  6. Fluoride8%
  7. Cadmium8%
  8. Iron8%
  9. Mercury7%
  10. Arsenic7%
  11. Nitrate6%
  12. Antimony6%
  13. Chromium5%
  14. Aluminium4%
  15. Copper4%
  16. Boron2%
  17. Trihalomethanes2%
  18. Manganese1%
  19. Selenium1%
  • Coliform Bacteria none found
  • E. coli none found
  • Conductivity 287 µS/cm
All 23 results as a table
SubstanceResultLegal limitShare of limit
Coliform Bacteria0 count/100mlMust be zeroNone found
E. coli0 count/100mlMust be zeroNone found
Colour1.8 mg/L Pt/Co20 mg/L Pt/Co
9%
Conductivity287 µS/cmNo legal limit–
Fluoride0.12 mg/L1.5 mg/L
8%
Nitrate3.1 mg/L50 mg/L
6%
Nitrite0.07 mg/L0.5 mg/L
14%
Hardness (as CaCO3)154 mg/LNo legal limit–
Aluminium0.0082 mg/L0.2 mg/L
4%
Antimony0.0003 mg/L0.005 mg/L
6%
Arsenic0.0007 mg/L0.01 mg/L
7%
Boron0.02 mg/L1 mg/L
2%
Cadmium0.0004 mg/L0.005 mg/L
8%
Chromium0.0025 mg/L0.05 mg/L
5%
Copper0.07 mg/L2 mg/L
4%
Iron0.015 mg/L0.2 mg/L
8%
Lead0.0013 mg/L0.01 mg/L
13%
Manganese0.0007 mg/L0.05 mg/L
1%
Mercury0.00007 mg/L0.001 mg/L
7%
Nickel0.0024 mg/L0.02 mg/L
12%
Selenium0.0004 mg/L0.04 mg/L
1%
Trihalomethanes0.002 mg/L0.1 mg/L
2%
Bromate0.001 mg/L0.01 mg/L
10%

154mg 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 Stratford Brook, rated good

The Environment Agency rated the Stratford Brook as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. 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 improved since the previous assessment.

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

KT24 in short

Tap water in KT24 (Guildford) is supplied by Thames Water in the Guildford Central zone and scores 9.4 out of 10, against an England and Wales average of 9.0. None of the 23 tested substances came close to a limit. The latest sample is from 31 December 2025.

  • 4th cleanest of 7 areas tested in GuildfordSquarely mid-table for Guildford, between GU12 on 9.4 and GU3 on 8.8.
  • Nothing tested came within 40% of its legal limitThe highest was Nitrite at 14% of the 0.5 mg/L maximum. See every reading
  • Moderately hard water at 154 mg/LSome scale over time in KT24, but not enough to justify a softener for most homes. How hardness is measured

Next door

GU18.8 out of 10 · 204 mg/LGU129.4 out of 10 · 154 mg/LGU29.4 out of 10 · 154 mg/LGU38.8 out of 10 · 138 mg/LGU49.1 out of 10 · 75 mg/LGU239.4 out of 10 · 154 mg/L

Questions about KT24 water

Is KT24 tap water safe to drink?

Based on the latest tests, KT24 (Guildford) water scores 9.4/10, which is safe. 0 of 23 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.

What contaminants are in KT24 water?

We tested 23 contaminants in KT24 water. None exceeded recommended safe levels.

Who supplies water in KT24?

KT24 (Guildford) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.

Is KT24 water hard or soft?

Water in KT24 (Guildford) has a hardness of 154 mg/L CaCO3, which is classified as moderately hard. This is a moderate hardness level.

Should I use a water filter in KT24?

KT24 water scored 9.4/10 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 KT24 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for KT24, 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 KT24?

The Environment Agency rated the Stratford Brook as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. 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 improved since the previous assessment. This is a rating of the river, not of tap water in KT24, 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 KT24

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
pH8.29 pHNone
Temperature18.6 °CNone
Conductivity419 µS/cmNone
Phosphate0.18 mg/LNone
Nitrite0.006 mg/L0.5 mg/L
Ammonia0.18 mg/L0.5 mg/L
Lead0.00005 mg/L0.01 mg/L
Zinc0.059 mg/LNone
Nickel0.0022 mg/L0.02 mg/L
Manganese0.00088 mg/L0.05 mg/L
Copper0.00095 mg/L2 mg/L
Iron0.034 mg/L0.2 mg/L
Dissolved Oxygen6.64 mg/LNone

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Source: Thames 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