Skip to main content
tapwater
England and Wales average 9.0

Tap water in PO15, WinchesterSafe to drink.

Supplied by Southern Water. 7,950 samples, 22 substances, latest on 23 April 2026. Everything is inside the legal limit. One result, nitrate, sits close to the line.

See the filter we recommendSee everything that was tested

9.2 / 10

The tank is as full as the score.

What to do about it

Waterdrop G3P600 Reverse Osmosis

Waterdrop G3P600 Reverse Osmosis

£550typical price

Removes nitrate, the result that stood out in PO15.

Check price at Waterdrop (opens in new tab)

Osmio PRO-III Ultimate Whole House

£499typical price

Removes nitrate, the result that stood out in PO15.

Check price at Osmio (opens in new tab)
ZeroWater 12-Cup Ready-Pour

ZeroWater 12-Cup Ready-Pour

£40typical price

Removes nitrate, the result that stood out in PO15.

Check price at Amazon (opens in new tab)

We earn a commission if you buy through these links, at no extra cost to you. It never changes which product we put first. How we make money

What's in a glass of PO15 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 81% of it. 17 of 18 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitCopper: 0.0077 mg/L, <1% of the 2 mg/L limitCopper<1%Nitrite: 0.004 mg/L, <1% of the 0.5 mg/L limitNitrite<1%Lead: 0.0002 mg/L, 2% of the 0.01 mg/L limitLead2%Chromium: 0.001 mg/L, 2% of the 0.05 mg/L limitChromium2%Selenium: 0.0008 mg/L, 2% of the 0.04 mg/L limitSelenium2%Cadmium: 0.00012 mg/L, 2% of the 0.005 mg/L limitCadmium2%Turbidity: 0.13 NTU, 3% of the 4 NTU limitTurbidity3%Manganese: 0.00178 mg/L, 4% of the 0.05 mg/L limitManganese4%Bromate: 0.0004 mg/L, 4% of the 0.01 mg/L limitBromate4%Antimony: 0.0002 mg/L, 4% of the 0.005 mg/L limitAntimony4%Nickel: 0.0009 mg/L, 5% of the 0.02 mg/L limitNickel5%Iron: 0.00928 mg/L, 5% of the 0.2 mg/L limitIron5%Aluminium: 0.0113 mg/L, 6% of the 0.2 mg/L limitAluminium6%Ammonia: 0.039 mg/L, 8% of the 0.5 mg/L limitAmmonia8%Arsenic: 0.001 mg/L, 10% of the 0.01 mg/L limitArsenic10%Trihalomethanes: 0.0142 mg/L, 14% of the 0.1 mg/L limitTrihalomethanes14%Colour: 3 mg/L Pt/Co, 15% of the 20 mg/L Pt/Co limitColour15%Nitrate: 40.4 mg/L, 81% of the 50 mg/L limitNitrate81%
  1. Nitrate81%
  2. Colour15%
  3. Trihalomethanes14%
  4. Arsenic10%
  5. Ammonia8%
  6. Aluminium6%
  7. Iron5%
  8. Nickel5%
  9. Bromate4%
  10. Antimony4%
  11. Manganese4%
  12. Turbidity3%
  13. Cadmium2%
  14. Lead2%
  15. Chromium2%
  16. Selenium2%
  17. Nitrite<1%
  18. Copper<1%
  • Coliform Bacteria none found
  • E. coli none found
  • pH 7.4 pH
  • Conductivity 561 µS/cm
All 22 results as a table
SubstanceResultLegal limitShare of limit
Nitrate40.4 mg/L50 mg/L
81%
Aluminium0.0113 mg/L0.2 mg/L
6%
Iron0.00928 mg/L0.2 mg/L
5%
Manganese0.00178 mg/L0.05 mg/L
4%
Coliform Bacteria0 count/100mlMust be zeroNone found
E. coli0 count/100mlMust be zeroNone found
Colour3 mg/L Pt/Co20 mg/L Pt/Co
15%
Turbidity0.13 NTU4 NTU
3%
pH7.4 pHNo legal limit–
Conductivity561 µS/cmNo legal limit–
Lead0.0002 mg/L0.01 mg/L
2%
Trihalomethanes0.0142 mg/L0.1 mg/L
14%
Bromate0.0004 mg/L0.01 mg/L
4%
Nitrite0.004 mg/L0.5 mg/L
<1%
Ammonia0.039 mg/L0.5 mg/L
8%
Copper0.0077 mg/L2 mg/L
<1%
Arsenic0.001 mg/L0.01 mg/L
10%
Cadmium0.00012 mg/L0.005 mg/L
2%
Chromium0.001 mg/L0.05 mg/L
2%
Nickel0.0009 mg/L0.02 mg/L
5%
Antimony0.0002 mg/L0.005 mg/L
4%
Selenium0.0008 mg/L0.04 mg/L
2%
Outside your tap

Your river is the Meon, rated good

The Environment Agency rated the Meon 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

Within 10 km

50

forever-chemical detections in nearby rivers and groundwater

At 3 sites. The highest was PFOS at 0.0059 µg/L, at RSN1377 West Common Stream at Imber Way, 8.9 km away, in October 2025. These are river and borehole samples, not tests of your tap water.

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

PO15 in short

Tap water in PO15 (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 23 April 2026.

  • Nitrate is within its legal limit but flagged, at 81% 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
  • 6th cleanest of 7 areas tested in Winchester1 area in Winchester scored lower. The best is SO21 on 9.3.
  • PFAS found at 3 monitoring sites within 10 kmThose are river and groundwater samples, not tap water. The highest was PFOS about 8.9 km away. What was measured

Next door

SO329.3 out of 10 · 276 mg/LSO219.3 out of 10 · 276 mg/LSO229.3 out of 10 · 276 mg/LSO259.3 out of 10 · 276 mg/LSO239.3 out of 10 · 276 mg/LSO249.2 out of 10 · 276 mg/LPO149.2 out of 10

Questions about PO15 water

Is PO15 tap water safe to drink?

Based on the latest tests, PO15 (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 PO15 water?

We tested 22 contaminants in PO15 water. 1 were flagged, including Nitrate. 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 PO15?

PO15 (Winchester) is supplied by Southern Water. You can view their full profile and compliance data on our supplier page.

Should I use a water filter in PO15?

With 1 contaminant above recommended levels in PO15, 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 PO15 water?

The tap-water tests we hold for PO15 do not include a PFAS result. Environment Agency monitoring found PFAS in 50 river and groundwater samples from 3 sites within 10 km of PO15, the highest being PFOS at 0.0059 µg/L about 8.9 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 river near PO15?

The Environment Agency rated the Meon 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 PO15, which is treated before it reaches homes.

Keep reading

PFAS explainedNitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map

River and groundwater readings near PO15

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
pH7.88 pHNone
Temperature18.3 °CNone
Conductivity1242 µS/cmNone
Ammonia0.044 mg/L0.5 mg/L
Nitrate4.4 mg/L50 mg/L
Nitrite0.046 mg/L0.5 mg/L
Phosphate0.5 mg/LNone
Dissolved Oxygen8.15 mg/LNone

Get alerts for your area

We'll email you when water quality data changes for PO15.

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