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tapwater
England and Wales average 9.0

Tap water in SO17, SouthamptonSafe to drink.Very hard.

Supplied by Southern Water. 16,940 samples, 25 substances, latest on 29 April 2026. Everything is inside the legal limit, and nothing comes close to it.

Get softener quotes for SO17See everything that was tested

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 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.

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What's in a glass of SO17 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 75% of it. 20 of 21 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitChromium: 0.00019 mg/L, <1% of the 0.05 mg/L limitChromium<1%Cadmium: 0.000031 mg/L, <1% of the 0.005 mg/L limitCadmium<1%Copper: 0.018 mg/L, <1% of the 2 mg/L limitCopper<1%Lead: 0.00009 mg/L, <1% of the 0.01 mg/L limitLead<1%Selenium: 0.00044 mg/L, 1% of the 0.04 mg/L limitSelenium1%Antimony: 0.000068 mg/L, 1% of the 0.005 mg/L limitAntimony1%Nitrite: 0.009 mg/L, 2% of the 0.5 mg/L limitNitrite2%Boron: 0.0191 mg/L, 2% of the 1 mg/L limitBoron2%Arsenic: 0.0002 mg/L, 2% of the 0.01 mg/L limitArsenic2%Turbidity: 0.13 NTU, 3% of the 4 NTU limitTurbidity3%Manganese: 0.00178 mg/L, 4% of the 0.05 mg/L limitManganese4%Mercury: 0.00004 mg/L, 4% of the 0.001 mg/L limitMercury4%Iron: 0.00928 mg/L, 5% of the 0.2 mg/L limitIron5%Bromate: 0.00049 mg/L, 5% of the 0.01 mg/L limitBromate5%Fluoride: 0.08 mg/L, 5% of the 1.5 mg/L limitFluoride5%Aluminium: 0.0113 mg/L, 6% of the 0.2 mg/L limitAluminium6%Nickel: 0.00154 mg/L, 8% of the 0.02 mg/L limitNickel8%Ammonia: 0.039 mg/L, 8% of the 0.5 mg/L limitAmmonia8%Colour: 3 mg/L Pt/Co, 15% of the 20 mg/L Pt/Co limitColour15%Trihalomethanes: 0.0167 mg/L, 17% of the 0.1 mg/L limitTrihalomethanes17%Nitrate: 37.4 mg/L, 75% of the 50 mg/L limitNitrate75%
  1. Nitrate75%
  2. Trihalomethanes17%
  3. Colour15%
  4. Ammonia8%
  5. Nickel8%
  6. Aluminium6%
  7. Fluoride5%
  8. Bromate5%
  9. Iron5%
  10. Mercury4%
  11. Manganese4%
  12. Turbidity3%
  13. Arsenic2%
  14. Boron2%
  15. Nitrite2%
  16. Antimony1%
  17. Selenium1%
  18. Copper<1%
  19. Lead<1%
  20. Cadmium<1%
  21. Chromium<1%
  • Coliform Bacteria none found
  • E. coli none found
  • pH 7.6 pH
  • Conductivity 562 µS/cm
All 25 results as a table
SubstanceResultLegal limitShare of limit
Nitrate37.4 mg/L50 mg/L
75%
Nitrite0.009 mg/L0.5 mg/L
2%
Ammonia0.039 mg/L0.5 mg/L
8%
Copper0.018 mg/L2 mg/L
<1%
Arsenic0.0002 mg/L0.01 mg/L
2%
Cadmium0.000031 mg/L0.005 mg/L
<1%
Chromium0.00019 mg/L0.05 mg/L
<1%
Nickel0.00154 mg/L0.02 mg/L
8%
Lead0.00009 mg/L0.01 mg/L
<1%
Antimony0.000068 mg/L0.005 mg/L
1%
Selenium0.00044 mg/L0.04 mg/L
1%
Coliform Bacteria0 count/100mlMust be zeroNone found
E. coli0 count/100mlMust be zeroNone found
Trihalomethanes0.0167 mg/L0.1 mg/L
17%
Bromate0.00049 mg/L0.01 mg/L
5%
Colour3 mg/L Pt/Co20 mg/L Pt/Co
15%
Turbidity0.13 NTU4 NTU
3%
pH7.6 pHNo legal limit–
Iron0.00928 mg/L0.2 mg/L
5%
Conductivity562 µS/cmNo legal limit–
Aluminium0.0113 mg/L0.2 mg/L
6%
Manganese0.00178 mg/L0.05 mg/L
4%
Boron0.0191 mg/L1 mg/L
2%
Fluoride0.08 mg/L1.5 mg/L
5%
Mercury0.00004 mg/L0.001 mg/L
4%

276mg of limescale minerals in every litre, typical for the SO area. SO17 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.

Soft400 mg/L

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Outside your tap

Your estuary is the Southampton Water, rated moderate

The Environment Agency rated the Southampton Water as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by nitrogen. 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

Within 10 km

257

forever-chemical detections in nearby rivers and groundwater

At 8 sites. The highest was PFOS at 0.011 µg/L, at Tadburn Lake at Romsey By-Pass, 9.9 km away, in March 2024. These are river and borehole samples, not tests of your tap water.

Every PFAS sample around Southampton · Which filters remove PFAS · PFAS explained

SO17 in short

Tap water in SO17 (Southampton) is supplied by Southern Water in the Southampton Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 25 tested substances came close to a limit. The latest sample is from 29 April 2026.

  • Nitrate is the reading closest to its limit, at 75% of the 50 mg/L maximumIt passed, but with less headroom than anything else tested here. Worth watching in the next round of results. See every reading
  • 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
  • 4th cleanest of 6 areas tested in SouthamptonSquarely mid-table for Southampton, between SO18 on 9.4 and SO14 on 8.9. Every area in Southampton

Next door

SO159.3 out of 10 · 276 mg/LSO169.3 out of 10 · 276 mg/LSO148.9 out of 10 · 276 mg/LSO189.4 out of 10 · 276 mg/LSO199.3 out of 10 · 276 mg/L

Questions about SO17 water

Is SO17 tap water safe to drink?

Based on the latest tests, SO17 (Southampton) water scores 9.3/10, which is safe. 0 of 25 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.

What contaminants are in SO17 water?

We tested 25 contaminants in SO17 water. None exceeded recommended safe levels. 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 SO17?

SO17 (Southampton) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.

Is SO17 water hard or soft?

No hardness reading has been published for SO17 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 SO17?

SO17 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 SO17 water?

The tap-water tests we hold for SO17 do not include a PFAS result. Environment Agency monitoring found PFAS in 257 river and groundwater samples from 8 sites within 10 km of SO17, the highest being PFOS at 0.011 µg/L about 9.9 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 estuary near SO17?

The Environment Agency rated the Southampton Water as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by nitrogen. 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 estuary, not of tap water in SO17, which is treated before it reaches homes.

Keep reading

PFAS explainedHow to test your waterBest water filtersFilter shower headsWater testing kitsAll of SouthamptonUK water rankingsWater hardness checkerWater hardness map

River and groundwater readings near SO17

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.

SubstanceReadingDrinking water limit
pH8.29 pHNone
Temperature19.2 °CNone
Conductivity593 µS/cmNone
Nitrate8.1 mg/L50 mg/L
Nitrite0.011 mg/L0.5 mg/L
Phosphate0.031 mg/LNone
Zinc0.0013 mg/LNone
Nickel0.00077 mg/L0.02 mg/L
Turbidity1.3 NTU4 NTU
Copper0.00088 mg/L2 mg/L
Dissolved Oxygen9.44 mg/LNone
Ammonia0.052 mg/L0.5 mg/L

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We'll email you when water quality data changes for SO17.

Source: Southern Water test results, published through the Stream Water Data Portal; rivers and PFAS from the Environment Agency. Page updated . How we score · Where the data comes from