Tap water in SP10, Test ValleySafe to drink.Very hard.
Supplied by Southern Water. 22,005 samples, 23 substances, latest on 27 April 2026. Everything is inside the legal limit, and nothing comes close to it.
9.4 / 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 297 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 SP10 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 66% of it. 18 of 19 substances used under a quarter of theirs.
- Nitrate66%
- Colour15%
- Lead9%
- Ammonia8%
- Trihalomethanes6%
- Aluminium6%
- Iron5%
- Mercury4%
- Manganese4%
- Nickel3%
- Turbidity3%
- Copper2%
- Nitrite2%
- Arsenic2%
- Bromate1%
- Selenium1%
- Antimony<1%
- Chromium<1%
- Cadmium<1%
- Coliform Bacteria none found
- E. coli none found
- pH 7.2 pH
- Conductivity 546 µS/cm
All 23 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Manganese | 0.00178 mg/L | 0.05 mg/L | 4% |
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Aluminium | 0.0113 mg/L | 0.2 mg/L | 6% |
| Iron | 0.00928 mg/L | 0.2 mg/L | 5% |
| pH | 7.2 pH | No legal limit | – |
| Lead | 0.00089 mg/L | 0.01 mg/L | 9% |
| Conductivity | 546 µS/cm | No legal limit | – |
| Nitrate | 32.9 mg/L | 50 mg/L | 66% |
| Colour | 3 mg/L Pt/Co | 20 mg/L Pt/Co | 15% |
| Turbidity | 0.13 NTU | 4 NTU | 3% |
| Trihalomethanes | 0.00636 mg/L | 0.1 mg/L | 6% |
| Cadmium | 0.000031 mg/L | 0.005 mg/L | <1% |
| Chromium | 0.00034 mg/L | 0.05 mg/L | <1% |
| Nickel | 0.00067 mg/L | 0.02 mg/L | 3% |
| Antimony | 0.000041 mg/L | 0.005 mg/L | <1% |
| Selenium | 0.00047 mg/L | 0.04 mg/L | 1% |
| Nitrite | 0.009 mg/L | 0.5 mg/L | 2% |
| Ammonia | 0.039 mg/L | 0.5 mg/L | 8% |
| Copper | 0.0481 mg/L | 2 mg/L | 2% |
| Arsenic | 0.00018 mg/L | 0.01 mg/L | 2% |
| Bromate | 0.00013 mg/L | 0.01 mg/L | 1% |
| Mercury | 0.00004 mg/L | 0.001 mg/L | 4% |
297mg of limescale minerals in every litre, typical for the SP area. SP10 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 SP10
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Your river is the Anton - Upper, rated good
The Environment Agency rated the Anton - Upper as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. 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
SP10 in short
Tap water in SP10 (Test Valley) is supplied by Southern Water in the Test Valley Central zone and scores 9.4 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 27 April 2026.
- The cleanest tap water of the 5 areas tested in Test ValleySP10 scores 9.4 out of 10, ahead of SO20 in second place on 9.3.
- Nitrate is the reading closest to its limit, at 66% of the 50 mg/L maximumIt passed with room to spare, and everything else tested sat further below its limit. See every reading
- Very hard water at 297 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles across the SP postcode area. How hardness is measured
Questions about SP10 water
Is SP10 tap water safe to drink?
Based on the latest tests, SP10 (Test Valley) water scores 9.4/10, which is safe. 0 of 23 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.
What contaminants are in SP10 water?
We tested 23 contaminants in SP10 water. None exceeded recommended safe levels.
Who supplies water in SP10?
SP10 (Test Valley) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.
Is SP10 water hard or soft?
No hardness reading has been published for SP10 itself. Across the SP postcode area the typical value is 297 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 SP10?
SP10 water scored 9.4/10 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 SP10 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for SP10, 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 SP10?
The Environment Agency rated the Anton - Upper as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. 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 SP10, 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 SP10
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 SP10.