Tap water in SN9, WiltshireSafe to drink.Very hard.
Supplied by Thames Water. 73 samples, 23 substances, latest on 31 December 2025. Everything is inside the legal limit, and nothing comes close to it.
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
Hard water: compare softener quotes
At 235 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.
ZeroWater 12-Cup Ready-Pour
£40typical price
Households concerned about PFAS and heavy metals
Waterdrop 10UA Under Sink
£70typical price
High-volume under-sink filtration without RO complexity
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What's in a glass of SN9 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.
Fluoride came closest to a limit, at 19% of it. 19 of 19 substances used under a quarter of theirs.
- Fluoride19%
- Nitrite14%
- Bromate10%
- Lead9%
- Colour9%
- Cadmium8%
- Mercury7%
- Arsenic7%
- Nickel7%
- Nitrate7%
- Selenium7%
- Antimony6%
- Chromium5%
- Aluminium4%
- Trihalomethanes4%
- Iron3%
- Boron2%
- Manganese1%
- Copper1%
- Coliform Bacteria none found
- E. coli none found
- Conductivity 421 µS/cm
All 23 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Colour | 1.8 mg/L Pt/Co | 20 mg/L Pt/Co | 9% |
| Conductivity | 421 µS/cm | No legal limit | – |
| Fluoride | 0.28 mg/L | 1.5 mg/L | 19% |
| Nitrate | 3.4 mg/L | 50 mg/L | 7% |
| Nitrite | 0.07 mg/L | 0.5 mg/L | 14% |
| Hardness (as CaCO3) | 235 mg/L | No legal limit | – |
| Aluminium | 0.0082 mg/L | 0.2 mg/L | 4% |
| Antimony | 0.0003 mg/L | 0.005 mg/L | 6% |
| Arsenic | 0.0007 mg/L | 0.01 mg/L | 7% |
| Boron | 0.02 mg/L | 1 mg/L | 2% |
| Cadmium | 0.0004 mg/L | 0.005 mg/L | 8% |
| Chromium | 0.0025 mg/L | 0.05 mg/L | 5% |
| Copper | 0.02 mg/L | 2 mg/L | 1% |
| Iron | 0.007 mg/L | 0.2 mg/L | 3% |
| Lead | 0.0009 mg/L | 0.01 mg/L | 9% |
| Manganese | 0.0006 mg/L | 0.05 mg/L | 1% |
| Mercury | 0.00007 mg/L | 0.001 mg/L | 7% |
| Nickel | 0.0014 mg/L | 0.02 mg/L | 7% |
| Selenium | 0.0026 mg/L | 0.04 mg/L | 7% |
| Trihalomethanes | 0.004 mg/L | 0.1 mg/L | 4% |
| Bromate | 0.001 mg/L | 0.01 mg/L | 10% |
235mg of limescale minerals in every litre
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 SN9
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Your river is the Hampshire Avon (East) and Woodborough Stream, rated poor
The Environment Agency rated the Hampshire Avon (East) and Woodborough Stream 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. Its ecological rating has dropped since the previous assessment.
None of this is a test of your tap water. Environment Agency record · River health across England
SN9 in short
Tap water in SN9 (Wiltshire) is supplied by Thames Water in the Wiltshire Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 23 tested substances came close to a limit. The latest sample is from 31 December 2025.
- The cleanest tap water of the 19 areas tested in WiltshireSN9 scores 9.3 out of 10, ahead of BA13 in second place on 8.8.
- Scores higher than all 10 neighbouring districtsThe nearest rival is BA13 on 8.8, against 9.3 here. Compare with BA13
- Hard water at 235 mg/LHard starts at 180 mg/L, the point where a softener begins to pay for itself. Limescale will build up in SN9. How hardness is measured
Questions about SN9 water
Is SN9 tap water safe to drink?
Based on the latest tests, SN9 (Wiltshire) water scores 9.3/10, which is safe. 0 of 23 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.
What contaminants are in SN9 water?
We tested 23 contaminants in SN9 water. None exceeded recommended safe levels.
Who supplies water in SN9?
SN9 (Wiltshire) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.
Is SN9 water hard or soft?
Water in SN9 (Wiltshire) has a hardness of 235 mg/L CaCO3, which is classified as hard. Hard water can cause limescale buildup. A water softener or filter jug may help.
Should I use a water filter in SN9?
SN9 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 SN9 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for SN9, 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 SN9?
The Environment Agency rated the Hampshire Avon (East) and Woodborough Stream 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. Its ecological rating has dropped since the previous assessment. This is a rating of the river, not of tap water in SN9, which is treated before it reaches homes.
Keep reading
- Best Water Softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared, with real costs
- Do I Need a Water Softener?The hardness bands, the symptoms, and a postcode check
- UK Water Hardness MapIs your water hard or soft, and does it matter?
- Is UK Tap Water Safe?Everything you need to know about tap water safety in the UK
- Do I need a water softener?The hardness bands, the symptoms, and when the answer is no
- Best water softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared
- Water softener costUnit, fitting and salt, and how long the payback takes
- Installation explainedWhere it goes, the bypass tap, the drain, DIY or plumber
- Harvey vs KineticoThe two premium twin-cylinder brands, side by side
- Softener salt guideTablet, block or granular, and how much you get through
- Salt-free softenersConditioners and electronic descalers, honestly assessed
How to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near SN9
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.
Get alerts for your area
We'll email you when water quality data changes for SN9.