Tap water in RH11, Crawley2 results are over the limit.Slightly hard.
Supplied by South East Water. 10 substances, latest on 28 October 2026. Manganese and Iron came in above the legal limit. Everything else passed.
6.6 / 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 RH11 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.
Manganese is over its legal limit, at 720% of it.
- Manganese720%
- Iron365%
- Nitrite19%
- Nitrate11%
- Ammonia7%
- pH 7.27 pH
- Temperature 10.9 °C
- Conductivity 457 µS/cm
- Phosphate 0.06 mg/L
- Dissolved Oxygen 8.85 mg/L
All 10 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Manganese | 0.36 mg/L | 0.05 mg/L | 720% |
| Iron | 0.73 mg/L | 0.2 mg/L | 365% |
| pH | 7.27 pH | No legal limit | – |
| Temperature | 10.9 °C | No legal limit | – |
| Conductivity | 457 µS/cm | No legal limit | – |
| Ammonia | 0.037 mg/L | 0.5 mg/L | 7% |
| Nitrate | 5.3 mg/L | 50 mg/L | 11% |
| Nitrite | 0.096 mg/L | 0.5 mg/L | 19% |
| Phosphate | 0.06 mg/L | No legal limit | – |
| Dissolved Oxygen | 8.85 mg/L | No legal limit | – |
148mg of limescale minerals in every litre, typical for the RH area. RH11 has no reading of its own.
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.
Your river is the Mole upstream of Horley, rated moderate
The Environment Agency rated the Mole upstream of Horley as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by dissolved oxygen, 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
RH11 in short
Tap water in RH11 (Crawley) is supplied by South East Water in the Crawley Central zone and scores 6.6 out of 10, against an England and Wales average of 9.0. 2 of 10 tested substances were close to or over a limit. The latest sample is from 28 October 2026.
- Manganese was measured at 0.36 mg/L, 7.2 times the UK limitIt is the furthest over its limit of the 2 substances flagged here. See the full results
- 2.4 points below the national average of 9Below the typical tested district in the UK, which is worth knowing before you choose a filter. Compare every area
- Moderately hard water at 148 mg/LSome scale over time across the RH postcode area, but not enough to justify a softener for most homes. How hardness is measured
Next door
Questions about RH11 water
Is RH11 tap water safe to drink?
Based on the latest tests, RH11 (Crawley) water scores 6.6/10, which is mostly safe but has some issues. 2 of 10 tested contaminants exceeded recommended levels. Water is supplied by South East Water.
What contaminants are in RH11 water?
We tested 10 contaminants in RH11 water. 2 were flagged, including Manganese, Iron.
Who supplies water in RH11?
RH11 (Crawley) is supplied by South East Water. You can view their full profile and compliance data on our supplier page.
Is RH11 water hard or soft?
No hardness reading has been published for RH11 itself. Across the RH postcode area the typical value is 148 mg/L CaCO3, which is classified as moderately hard. This is a moderate hardness level.
Should I use a water filter in RH11?
With 2 contaminants above recommended levels in RH11, 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 RH11 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for RH11, 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 RH11?
The Environment Agency rated the Mole upstream of Horley as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by dissolved oxygen, 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 RH11, which is treated before it reaches homes.
Keep reading
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- Best Water Filter Jug UKBRITA vs ZeroWater vs the rest, tested against real data
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