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tapwater
England and Wales average 9.0

Tap water in RH4, Mole ValleySafe to drink.Slightly hard.

Supplied by Thames Water. 74 samples, 23 substances, latest on 31 December 2025. Everything is inside the legal limit. One result, nitrite, sits close to the line.

See the filter we recommendSee everything that was tested

8.8 / 10

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

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What's in a glass of RH4 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 76% of it. 16 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%Copper: 0.03 mg/L, 2% of the 2 mg/L limitCopper2%Boron: 0.03 mg/L, 3% of the 1 mg/L limitBoron3%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%Iron: 0.01 mg/L, 5% of the 0.2 mg/L limitIron5%Antimony: 0.0003 mg/L, 6% of the 0.005 mg/L limitAntimony6%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%Cadmium: 0.0004 mg/L, 8% of the 0.005 mg/L limitCadmium8%Fluoride: 0.13 mg/L, 9% of the 1.5 mg/L limitFluoride9%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: 0.0022 mg/L, 11% of the 0.02 mg/L limitNickel11%Lead: 0.0012 mg/L, 12% of the 0.01 mg/L limitLead12%Nitrate: 18.9 mg/L, 38% of the 50 mg/L limitNitrate38%Trihalomethanes: 0.04 mg/L, 40% of the 0.1 mg/L limitTrihalomethanes40%Nitrite: 0.38 mg/L, 76% of the 0.5 mg/L limitNitrite76%
  1. Nitrite76%
  2. Trihalomethanes40%
  3. Nitrate38%
  4. Lead12%
  5. Nickel11%
  6. Bromate10%
  7. Colour9%
  8. Fluoride9%
  9. Cadmium8%
  10. Mercury7%
  11. Arsenic7%
  12. Antimony6%
  13. Chromium5%
  14. Iron5%
  15. Aluminium4%
  16. Boron3%
  17. Copper2%
  18. Manganese1%
  19. Selenium1%
  • Coliform Bacteria none found
  • E. coli none found
  • Conductivity 363 µS/cm
All 23 results as a table
SubstanceResultLegal limitShare of limit
Nitrite0.38 mg/L0.5 mg/L
76%
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%
Conductivity363 µS/cmNo legal limit–
Fluoride0.13 mg/L1.5 mg/L
9%
Nitrate18.9 mg/L50 mg/L
38%
Hardness (as CaCO3)138 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%
Boron0.03 mg/L1 mg/L
3%
Cadmium0.0004 mg/L0.005 mg/L
8%
Chromium0.0025 mg/L0.05 mg/L
5%
Copper0.03 mg/L2 mg/L
2%
Iron0.01 mg/L0.2 mg/L
5%
Lead0.0012 mg/L0.01 mg/L
12%
Manganese0.0007 mg/L0.05 mg/L
1%
Mercury0.00007 mg/L0.001 mg/L
7%
Nickel0.0022 mg/L0.02 mg/L
11%
Selenium0.0004 mg/L0.04 mg/L
1%
Trihalomethanes0.04 mg/L0.1 mg/L
40%
Bromate0.001 mg/L0.01 mg/L
10%

138mg 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 Pipp Brook, rated poor

The Environment Agency rated the Pipp Brook 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 water plants and algae, fish 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.

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

RH4 in short

Tap water in RH4 (Mole Valley) is supplied by Thames Water in the Mole Valley Central zone and scores 8.8 out of 10, against an England and Wales average of 9.0. 1 of 23 tested substances was close to or over a limit. The latest sample is from 31 December 2025.

  • Nitrite is within its legal limit but flagged, at 76% of the 0.5 mg/L maximumAnything over three quarters of a limit is flagged here as worth watching. It has not gone over. See every reading
  • 5th cleanest of 6 areas tested in Mole Valley1 area in Mole Valley scored lower. The best is RH3 on 9.4.
  • Moderately hard water at 138 mg/LSome scale over time in RH4, but not enough to justify a softener for most homes. How hardness is measured

Next door

KT238.8 out of 10 · 204 mg/LKT217.8 out of 10 · 287 mg/LKT228.8 out of 10 · 141 mg/LRH39.4 out of 10 · 154 mg/LRH59.1 out of 10 · 75 mg/L

Questions about RH4 water

Is RH4 tap water safe to drink?

Based on the latest tests, RH4 (Mole Valley) water scores 8.8/10, which is safe. 1 of 23 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.

What contaminants are in RH4 water?

We tested 23 contaminants in RH4 water. 1 were flagged, including Nitrite.

Who supplies water in RH4?

RH4 (Mole Valley) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.

Is RH4 water hard or soft?

Water in RH4 (Mole Valley) has a hardness of 138 mg/L CaCO3, which is classified as moderately hard. This is a moderate hardness level.

Should I use a water filter in RH4?

With 1 contaminant above recommended levels in RH4, a water filter could help. A filter jug or under-sink filter can reduce most common contaminants. See our filter recommendations for your area.

Are there PFAS forever chemicals in RH4 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for RH4, 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 RH4?

The Environment Agency rated the Pipp Brook 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 water plants and algae, fish 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. This is a rating of the river, not of tap water in RH4, which is treated before it reaches homes.

Keep reading

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

River and groundwater readings near RH4

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
pH7.7 pHNone
Temperature20.4 °CNone
Conductivity932 µS/cmNone
Nitrate18 mg/L50 mg/L
Nitrite0.025 mg/L0.5 mg/L
Phosphate0.44 mg/LNone
Dissolved Oxygen7.35 mg/LNone
Ammonia0.078 mg/L0.5 mg/L
Chromium0.0043 mg/L0.05 mg/L
Zinc0.0182 mg/LNone
PFAS (total)0.00528 µg/LNone

Get alerts for your area

We'll email you when water quality data changes for RH4.

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