Tap water in SO24, WinchesterSafe to drink.Very hard.
Supplied by Southern Water. 8,235 samples, 22 substances, latest on 29 April 2026. Everything is inside the legal limit. One result, nitrate, sits close to the line.
9.2 / 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 276 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
Removes nitrate, the result that stood out in SO24.
Osmio PRO-III Ultimate Whole House
£499typical price
Removes nitrate, the result that stood out in SO24.
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What's in a glass of SO24 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.
Nitrate came closest to a limit, at 86% of it. 17 of 18 substances used under a quarter of theirs.
- Nitrate86%
- Colour15%
- Trihalomethanes11%
- Arsenic10%
- Ammonia8%
- Antimony6%
- Aluminium6%
- Iron5%
- Nickel5%
- Manganese4%
- Turbidity3%
- Copper2%
- Cadmium2%
- Chromium2%
- Nitrite2%
- Bromate1%
- Selenium1%
- Lead<1%
- pH 8.1 pH
- Coliform Bacteria none found
- E. coli none found
- Conductivity 519 µS/cm
All 22 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Nitrate | 43.1 mg/L | 50 mg/L | 86% |
| pH | 8.1 pH | No legal limit | – |
| Aluminium | 0.0113 mg/L | 0.2 mg/L | 6% |
| Iron | 0.00928 mg/L | 0.2 mg/L | 5% |
| Manganese | 0.00178 mg/L | 0.05 mg/L | 4% |
| Lead | 0.00009 mg/L | 0.01 mg/L | <1% |
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Conductivity | 519 µS/cm | No legal limit | – |
| Trihalomethanes | 0.0108 mg/L | 0.1 mg/L | 11% |
| Nitrite | 0.009 mg/L | 0.5 mg/L | 2% |
| Ammonia | 0.039 mg/L | 0.5 mg/L | 8% |
| Copper | 0.048 mg/L | 2 mg/L | 2% |
| Arsenic | 0.001 mg/L | 0.01 mg/L | 10% |
| Cadmium | 0.00012 mg/L | 0.005 mg/L | 2% |
| Chromium | 0.001 mg/L | 0.05 mg/L | 2% |
| Nickel | 0.0009 mg/L | 0.02 mg/L | 5% |
| Antimony | 0.0003 mg/L | 0.005 mg/L | 6% |
| Selenium | 0.0005 mg/L | 0.04 mg/L | 1% |
| Colour | 3 mg/L Pt/Co | 20 mg/L Pt/Co | 15% |
| Turbidity | 0.13 NTU | 4 NTU | 3% |
| Bromate | 0.00015 mg/L | 0.01 mg/L | 1% |
276mg of limescale minerals in every litre, typical for the SO area. SO24 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 SO24
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Your river is the Arle, rated moderate
The Environment Agency rated the Arle as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. 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
SO24 in short
Tap water in SO24 (Winchester) is supplied by Southern Water in the Winchester Central zone and scores 9.2 out of 10, against an England and Wales average of 9.0. 1 of 22 tested substances was close to or over a limit. The latest sample is from 29 April 2026.
- Nitrate is within its legal limit but flagged, at 86% of the 50 mg/L maximumAnything over three quarters of a limit is flagged here as worth watching. It has not gone over. See every reading
- The lowest score of the 7 areas tested in WinchesterSO24 scores 9.2 out of 10. The best in Winchester, SO21, scores 9.3.
- Very hard water at 276 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles across the SO postcode area. How hardness is measured
Questions about SO24 water
Is SO24 tap water safe to drink?
Based on the latest tests, SO24 (Winchester) water scores 9.2/10, which is safe. 1 of 22 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.
What contaminants are in SO24 water?
We tested 22 contaminants in SO24 water. 1 were flagged, including Nitrate.
Who supplies water in SO24?
SO24 (Winchester) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.
Is SO24 water hard or soft?
No hardness reading has been published for SO24 itself. Across the SO postcode area the typical value is 276 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 SO24?
With 1 contaminant above recommended levels in SO24, 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 SO24 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for SO24, 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 SO24?
The Environment Agency rated the Arle as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. 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 SO24, 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?
- 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
Nitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near SO24
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 SO24.