Tap water in HP9, Buckinghamshire3 results are over the limit.Very hard.
Supplied by Thames Water. 12 substances, latest on 25 March 2026. Ammonia, Manganese and Iron came in above the legal limit. Everything else passed.
4.5 / 10
The tank is as full as the score. The specks are the minerals that make water hard.
What to do about it
Hard water: compare softener quotes
At 299 mg/L a softener is the only thing that stops limescale. Filters do not soften water.
It pays for itself in most homes at this hardness, through a boiler that stays efficient and appliances that last.
Waterdrop G3P600 Reverse Osmosis
£550typical price
Maximum contaminant removal including PFAS and fluoride
Waterdrop 10UA Under Sink
£70typical price
High-volume under-sink filtration without RO complexity
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What's in a glass of HP9 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.
Iron is over its legal limit, at 11150% of it.
- Iron11150%
- Ammonia6560%
- Manganese3760%
- Boron56%
- Nitrate26%
- Fluoride6%
- Copper<1%
- Temperature 10 °C
- Conductivity 718 µS/cm
- pH 7.21 pH
- Dissolved Oxygen 10.1 mg/L
All 12 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Ammonia | 32.8 mg/L | 0.5 mg/L | 6560% |
| Manganese | 1.88 mg/L | 0.05 mg/L | 3760% |
| Iron | 22.3 mg/L | 0.2 mg/L | 11150% |
| Temperature | 10 °C | No legal limit | – |
| Conductivity | 718 µS/cm | No legal limit | – |
| Nitrate | 13 mg/L | 50 mg/L | 26% |
| pH | 7.21 pH | No legal limit | – |
| Dissolved Oxygen | 10.1 mg/L | No legal limit | – |
| Hardness (as CaCO3) | 534 mg/L | No legal limit | – |
| Fluoride | 0.09 mg/L | 1.5 mg/L | 6% |
| Boron | 0.562 mg/L | 1 mg/L | 56% |
| Copper | 0.0075 mg/L | 2 mg/L | <1% |
299mg of limescale minerals in every litre, typical for the HP area. HP9 has no reading of its own.
This is the water that furs up kettles
Very hard on the UK scale. It is fine to drink. It is hard on boilers, showers, skin and anything that heats water, and a jug or tap filter will not change that.
Softener quotes for HP9
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Your river is the Wye (High Wycombe fire station to Thames), rated poor
The Environment Agency rated the Wye (High Wycombe fire station to Thames) 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 and insects and other small river life. 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
HP9 in short
Tap water in HP9 (Buckinghamshire) is supplied by Thames Water in the Buckinghamshire Central zone and scores 4.5 out of 10, against an England and Wales average of 9.0. 3 of 12 tested substances were close to or over a limit. The latest sample is from 25 March 2026.
- Iron was measured at 22.3 mg/L, 112 times the UK limitIt is the furthest over its limit of the 3 substances flagged here. See the full results
- The lowest score of the 26 areas tested in BuckinghamshireHP9 scores 4.5 out of 10. The best in Buckinghamshire, HP19, scores 9.3.
- 4.5 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
Questions about HP9 water
Is HP9 tap water safe to drink?
Based on the latest tests, HP9 (Buckinghamshire) water scores 4.5/10, which is mostly safe but has some issues. 3 of 12 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.
What contaminants are in HP9 water?
We tested 12 contaminants in HP9 water. 3 were flagged, including Ammonia, Manganese, Iron.
Who supplies water in HP9?
HP9 (Buckinghamshire) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.
Is HP9 water hard or soft?
No hardness reading has been published for HP9 itself. Across the HP postcode area the typical value is 299 mg/L CaCO3, which is classified as very hard. Hard water can cause limescale buildup. A water softener or filter jug may help.
Should I use a water filter in HP9?
With 3 contaminants above recommended levels in HP9, 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 HP9 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for HP9, 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 HP9?
The Environment Agency rated the Wye (High Wycombe fire station to Thames) 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 and insects and other small river life. 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 HP9, which is treated before it reaches homes.
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