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tapwater
England and Wales average 9.0

Tap water in RH12, HorshamSafe to drink.Slightly hard.

Supplied by Southern Water. 15,933 samples, 22 substances, latest on 29 April 2026. Everything is inside the legal limit, and nothing comes close to it.

See the filter we recommendSee everything that was tested

9.3 / 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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Households concerned about PFAS and heavy metals

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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 RH12 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.

Nitrate came closest to a limit, at 44% of it. 16 of 18 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitCopper: 0.0015 mg/L, <1% of the 2 mg/L limitCopper<1%Nitrite: 0.004 mg/L, <1% of the 0.5 mg/L limitNitrite<1%Lead: 0.00009 mg/L, <1% of the 0.01 mg/L limitLead<1%Selenium: 0.0005 mg/L, 1% of the 0.04 mg/L limitSelenium1%Chromium: 0.001 mg/L, 2% of the 0.05 mg/L limitChromium2%Cadmium: 0.00012 mg/L, 2% of the 0.005 mg/L limitCadmium2%Turbidity: 0.13 NTU, 3% of the 4 NTU limitTurbidity3%Manganese: 0.00178 mg/L, 4% of the 0.05 mg/L limitManganese4%Bromate: 0.00039 mg/L, 4% of the 0.01 mg/L limitBromate4%Iron: 0.00928 mg/L, 5% of the 0.2 mg/L limitIron5%Aluminium: 0.0113 mg/L, 6% of the 0.2 mg/L limitAluminium6%Antimony: 0.0003 mg/L, 6% of the 0.005 mg/L limitAntimony6%Ammonia: 0.039 mg/L, 8% of the 0.5 mg/L limitAmmonia8%Arsenic: 0.001 mg/L, 10% of the 0.01 mg/L limitArsenic10%Nickel: 0.0024 mg/L, 12% of the 0.02 mg/L limitNickel12%Colour: 3 mg/L Pt/Co, 15% of the 20 mg/L Pt/Co limitColour15%Trihalomethanes: 0.0318 mg/L, 32% of the 0.1 mg/L limitTrihalomethanes32%Nitrate: 21.8 mg/L, 44% of the 50 mg/L limitNitrate44%
  1. Nitrate44%
  2. Trihalomethanes32%
  3. Colour15%
  4. Nickel12%
  5. Arsenic10%
  6. Ammonia8%
  7. Antimony6%
  8. Aluminium6%
  9. Iron5%
  10. Bromate4%
  11. Manganese4%
  12. Turbidity3%
  13. Cadmium2%
  14. Chromium2%
  15. Selenium1%
  16. Lead<1%
  17. Nitrite<1%
  18. Copper<1%
  • pH 8 pH
  • Coliform Bacteria none found
  • E. coli none found
  • Conductivity 414 µS/cm
All 22 results as a table
SubstanceResultLegal limitShare of limit
Colour3 mg/L Pt/Co20 mg/L Pt/Co
15%
Turbidity0.13 NTU4 NTU
3%
pH8 pHNo legal limit–
Aluminium0.0113 mg/L0.2 mg/L
6%
Iron0.00928 mg/L0.2 mg/L
5%
Manganese0.00178 mg/L0.05 mg/L
4%
Coliform Bacteria0 count/100mlMust be zeroNone found
E. coli0 count/100mlMust be zeroNone found
Conductivity414 µS/cmNo legal limit–
Nitrate21.8 mg/L50 mg/L
44%
Lead0.00009 mg/L0.01 mg/L
<1%
Copper0.0015 mg/L2 mg/L
<1%
Arsenic0.001 mg/L0.01 mg/L
10%
Cadmium0.00012 mg/L0.005 mg/L
2%
Chromium0.001 mg/L0.05 mg/L
2%
Nickel0.0024 mg/L0.02 mg/L
12%
Antimony0.0003 mg/L0.005 mg/L
6%
Selenium0.0005 mg/L0.04 mg/L
1%
Nitrite0.004 mg/L0.5 mg/L
<1%
Trihalomethanes0.0318 mg/L0.1 mg/L
32%
Ammonia0.039 mg/L0.5 mg/L
8%
Bromate0.00039 mg/L0.01 mg/L
4%

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 Boldings Brook, rated poor

The Environment Agency rated the Boldings 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 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

RH12 in short

Tap water in RH12 (Horsham) is supplied by Southern Water in the Horsham Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 22 tested substances came close to a limit. The latest sample is from 29 April 2026.

  • Nitrate is the reading closest to its limit, at 44% of the 50 mg/L maximumIt passed with room to spare, and everything else tested sat further below its limit. See every reading
  • 3rd cleanest of 5 areas tested in HorshamSquarely mid-table for Horsham, between BN44 on 9.4 and RH20 on 9.3.
  • Moderately hard water at 154 mg/LSome scale over time in RH12, but not enough to justify a softener for most homes. How hardness is measured

Next door

BN449.4 out of 10BN59.3 out of 10RH209.3 out of 10 · 148 mg/LRH139.3 out of 10 · 148 mg/L

Questions about RH12 water

Is RH12 tap water safe to drink?

Based on the latest tests, RH12 (Horsham) water scores 9.3/10, which is safe. 0 of 22 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.

What contaminants are in RH12 water?

We tested 22 contaminants in RH12 water. None exceeded recommended safe levels.

Who supplies water in RH12?

RH12 (Horsham) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.

Is RH12 water hard or soft?

Water in RH12 (Horsham) 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 RH12?

RH12 water scored 9.3/10 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 RH12 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for RH12, 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 RH12?

The Environment Agency rated the Boldings 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 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 RH12, 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 RH12

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
pH7.46 pHNone
Temperature18.6 °CNone
Conductivity385 µS/cmNone
Ammonia0.059 mg/L0.5 mg/L
Nitrate0.5 mg/L50 mg/L
Nitrite0.014 mg/L0.5 mg/L
Phosphate0.15 mg/LNone
Dissolved Oxygen5.55 mg/LNone
PFAS (total)0.0011 µg/LNone

Get alerts for your area

We'll email you when water quality data changes for RH12.

Source: Southern 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