Tap water in GU46, Hart2 results are over the limit.Slightly hard.
Supplied by Southern Water. 10 substances, latest on 7 October 2026. Ammonia and Nitrite came in above the legal limit. Everything else passed.
3.8 / 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 GU46 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.
Ammonia is over its legal limit, at 128% of it.
- Ammonia128%
- Nitrite114%
- Iron65%
- Nitrate48%
- Cadmium<1%
- pH 7.18 pH
- Temperature 15.8 °C
- Conductivity 988 µS/cm
- Phosphate 0.31 mg/L
- Dissolved Oxygen 4.58 mg/L
All 10 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Ammonia | 0.64 mg/L | 0.5 mg/L | 128% |
| Nitrite | 0.57 mg/L | 0.5 mg/L | 114% |
| pH | 7.18 pH | No legal limit | – |
| Temperature | 15.8 °C | No legal limit | – |
| Conductivity | 988 µS/cm | No legal limit | – |
| Nitrate | 24 mg/L | 50 mg/L | 48% |
| Phosphate | 0.31 mg/L | No legal limit | – |
| Dissolved Oxygen | 4.58 mg/L | No legal limit | – |
| Cadmium | 0.00002 mg/L | 0.005 mg/L | <1% |
| Iron | 0.13 mg/L | 0.2 mg/L | 65% |
154mg of limescale minerals in every litre, typical for the GU area. GU46 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 Blackwater (Hawley to Whitewater confluence at Bramshill), rated moderate
The Environment Agency rated the Blackwater (Hawley to Whitewater confluence at Bramshill) as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. 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
138
forever-chemical detections in nearby rivers and groundwater
At 2 sites. The highest was 6:2 FtSAB at 0.067 µg/L, at Blackwater at Gauging Station, Swallowfield, 9.2 km away, in January 2026. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Reading · Which filters remove PFAS · PFAS explained
GU46 in short
Tap water in GU46 (Hart) is supplied by Southern Water in the Hart Central zone and scores 3.8 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 7 October 2026.
- Ammonia was measured at 0.64 mg/L, 28% over the UK limitIt is the furthest over its limit of the 2 substances flagged here. See the full results
- The lowest score of the 6 areas tested in HartGU46 scores 3.8 out of 10. The best in Hart, RG27, scores 9.5.
- 5.2 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 GU46 water
Is GU46 tap water safe to drink?
Based on the latest tests, GU46 (Hart) water scores 3.8/10, which is below average and may need attention. 2 of 10 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.
What contaminants are in GU46 water?
We tested 10 contaminants in GU46 water. 2 were flagged, including Ammonia, Nitrite. PFAS (forever chemicals) were also measured in rivers and groundwater within 10 km, though not in the tap-water tests themselves.
Who supplies water in GU46?
GU46 (Hart) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.
Is GU46 water hard or soft?
No hardness reading has been published for GU46 itself. Across the GU postcode area the typical value is 154 mg/L CaCO3, which is classified as moderately hard. This is a moderate hardness level.
Should I use a water filter in GU46?
With 2 contaminants above recommended levels in GU46, a water filter could help. A reverse osmosis or activated carbon filter is recommended for PFAS removal. See our filter recommendations for your area.
Are there PFAS forever chemicals in GU46 water?
The tap-water tests we hold for GU46 do not include a PFAS result. Environment Agency monitoring found PFAS in 138 river and groundwater samples from 2 sites within 10 km of GU46, the highest being 6:2 FtSAB at 0.067 µg/L about 9.2 km away. These are environmental samples, not tests of tap water. The UK currently has no legal limit for PFAS in drinking water; the Drinking Water Inspectorate uses a 0.1 µg/L guideline for individual compounds. Reverse osmosis filters can reduce PFAS levels.
How clean is the river near GU46?
The Environment Agency rated the Blackwater (Hawley to Whitewater confluence at Bramshill) as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. 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 GU46, which is treated before it reaches homes.
Keep reading
- Best Filter for PFAS RemovalThe filters with independent certification to remove forever chemicals
- PFAS Forever ChemicalsWhat PFAS are and how to reduce your exposure at home
- Best Water Filters UKEvery filter type compared on what it actually removes
- Is UK Tap Water Safe?Everything you need to know about tap water safety in the UK
PFAS explainedNitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
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