Tap water in SN1, SwindonSafe to drink.Very hard.
Supplied by Thames Water. 76 samples, 23 substances, latest on 31 December 2025. Everything is inside the legal limit. One result, nitrite, sits close to the line.
8.6 / 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 268 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 SN1 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.
Nitrite came closest to a limit, at 100% of it. 17 of 19 substances used under a quarter of theirs.
- Nitrite100%
- Nitrate50%
- Lead19%
- Bromate14%
- Trihalomethanes11%
- Colour9%
- Cadmium8%
- Mercury7%
- Arsenic7%
- Nickel7%
- Fluoride6%
- Copper6%
- Antimony6%
- Chromium5%
- Aluminium4%
- Iron3%
- Boron2%
- Manganese2%
- Selenium1%
- Coliform Bacteria none found
- E. coli none found
- Conductivity 527 µS/cm
All 23 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Nitrite | 0.5 mg/L | 0.5 mg/L | 100% |
| 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 | 527 µS/cm | No legal limit | – |
| Fluoride | 0.09 mg/L | 1.5 mg/L | 6% |
| Nitrate | 25 mg/L | 50 mg/L | 50% |
| Hardness (as CaCO3) | 268 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 | 0.12 mg/L | 2 mg/L | 6% |
| Iron | 0.007 mg/L | 0.2 mg/L | 3% |
| Lead | 0.0019 mg/L | 0.01 mg/L | 19% |
| Manganese | 0.0008 mg/L | 0.05 mg/L | 2% |
| Mercury | 0.00007 mg/L | 0.001 mg/L | 7% |
| Nickel | 0.0013 mg/L | 0.02 mg/L | 7% |
| Selenium | 0.0004 mg/L | 0.04 mg/L | 1% |
| Trihalomethanes | 0.011 mg/L | 0.1 mg/L | 11% |
| Bromate | 0.0014 mg/L | 0.01 mg/L | 14% |
268mg 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 SN1
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Your river is the Ray (Wiltshire) source to Lydiard Brook, rated poor
The Environment Agency rated the Ray (Wiltshire) source to Lydiard 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 insects and other small river life 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
56
forever-chemical detections in nearby rivers and groundwater
At 7 sites. The highest was PFBS at 0.02 µg/L, at Ray at Seven Bridges, Cricklade, 9.1 km away, in August 2024. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Swindon · Which filters remove PFAS · PFAS explained
SN1 in short
Tap water in SN1 (Swindon) is supplied by Thames Water in the Swindon Central zone and scores 8.6 out of 10, against an England and Wales average of 9.0. 1 of 23 tested substances was close to or over a limit. The latest sample is from 31 December 2025.
- Nitrite is within its legal limit but flagged, at 100% of the 0.5 mg/L maximumAnything over three quarters of a limit is flagged here as worth watching. It has not gone over. See every reading
- Very hard water at 268 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles in SN1. How hardness is measured
- 2nd cleanest of 8 areas tested in SwindonOnly 1 area in Swindon scored higher. The best is SN25 on 8.7. Every area in Swindon
Questions about SN1 water
Is SN1 tap water safe to drink?
Based on the latest tests, SN1 (Swindon) water scores 8.6/10, which is safe. 1 of 23 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.
What contaminants are in SN1 water?
We tested 23 contaminants in SN1 water. 1 were flagged, including 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 SN1?
SN1 (Swindon) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.
Is SN1 water hard or soft?
Water in SN1 (Swindon) has a hardness of 268 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 SN1?
With 1 contaminant above recommended levels in SN1, 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 SN1 water?
The tap-water tests we hold for SN1 do not include a PFAS result. Environment Agency monitoring found PFAS in 56 river and groundwater samples from 7 sites within 10 km of SN1, the highest being PFBS at 0.02 µg/L about 9.1 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 SN1?
The Environment Agency rated the Ray (Wiltshire) source to Lydiard 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 insects and other small river life 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 SN1, 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 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?
- Best Water Filters UKEvery filter type compared on what it actually removes
- 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
PFAS explainedNitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsAll of SwindonUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near SN1
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 SN1.