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England and Wales average 9.0

Tap water in PO3, PortsmouthNitrite is over the limit.

Supplied by Portsmouth Water. 3,081 samples, 21 substances, latest on 31 December 2024. Nitrite came in above the legal limit. Everything else passed.

See the filter we recommendSee everything that was tested

8.4 / 10

The tank is as full as the score.

What to do about it

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What's in a glass of PO3 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 is over its legal limit, at 131% of it.

0%25%50%75%limitLegal limitSelenium: 0.0008 mg/L, 2% of the 0.04 mg/L limitSelenium2%Antimony: 0.0002 mg/L, 4% of the 0.005 mg/L limitAntimony4%Mercury: 0.00004 mg/L, 4% of the 0.001 mg/L limitMercury4%Cadmium: 0.00022 mg/L, 4% of the 0.005 mg/L limitCadmium4%Chromium: 0.0023 mg/L, 5% of the 0.05 mg/L limitChromium5%Lead: 0.0005 mg/L, 5% of the 0.01 mg/L limitLead5%Manganese: 0.0025 mg/L, 5% of the 0.05 mg/L limitManganese5%Aluminium: 0.0106 mg/L, 5% of the 0.2 mg/L limitAluminium5%Nickel: 0.0013 mg/L, 7% of the 0.02 mg/L limitNickel7%Fluoride: 0.1 mg/L, 7% of the 1.5 mg/L limitFluoride7%Iron: 0.0138 mg/L, 7% of the 0.2 mg/L limitIron7%Bromate: 0.0008 mg/L, 8% of the 0.01 mg/L limitBromate8%Copper: 0.172 mg/L, 9% of the 2 mg/L limitCopper9%Turbidity: 0.385 NTU, 10% of the 4 NTU limitTurbidity10%Colour: 1.93 mg/L Pt/Co, 10% of the 20 mg/L Pt/Co limitColour10%Arsenic: 0.001 mg/L, 10% of the 0.01 mg/L limitArsenic10%Boron: 0.14 mg/L, 14% of the 1 mg/L limitBoron14%Trihalomethanes: 0.0195 mg/L, 20% of the 0.1 mg/L limitTrihalomethanes20%Nitrate: 33 mg/L, 66% of the 50 mg/L limitNitrate66%Nitrite: 0.654 mg/L, 131% of the 0.5 mg/L limitNitrite131%
  1. Nitrite131%
  2. Nitrate66%
  3. Trihalomethanes20%
  4. Boron14%
  5. Arsenic10%
  6. Colour10%
  7. Turbidity10%
  8. Copper9%
  9. Bromate8%
  10. Iron7%
  11. Fluoride7%
  12. Nickel7%
  13. Aluminium5%
  14. Lead5%
  15. Manganese5%
  16. Chromium5%
  17. Cadmium4%
  18. Antimony4%
  19. Mercury4%
  20. Selenium2%
  • Conductivity 520 µS/cm
All 21 results as a table
SubstanceResultLegal limitShare of limit
Nitrite0.654 mg/L0.5 mg/L
131%
Aluminium0.0106 mg/L0.2 mg/L
5%
Iron0.0138 mg/L0.2 mg/L
7%
Manganese0.0025 mg/L0.05 mg/L
5%
Turbidity0.385 NTU4 NTU
10%
Conductivity520 µS/cmNo legal limit–
Nitrate33 mg/L50 mg/L
66%
Colour1.93 mg/L Pt/Co20 mg/L Pt/Co
10%
Lead0.0005 mg/L0.01 mg/L
5%
Nickel0.0013 mg/L0.02 mg/L
7%
Copper0.172 mg/L2 mg/L
9%
Fluoride0.1 mg/L1.5 mg/L
7%
Antimony0.0002 mg/L0.005 mg/L
4%
Arsenic0.001 mg/L0.01 mg/L
10%
Selenium0.0008 mg/L0.04 mg/L
2%
Bromate0.0008 mg/L0.01 mg/L
8%
Mercury0.00004 mg/L0.001 mg/L
4%
Boron0.14 mg/L1 mg/L
14%
Chromium0.0023 mg/L0.05 mg/L
5%
Cadmium0.00022 mg/L0.005 mg/L
4%
Trihalomethanes0.0195 mg/L0.1 mg/L
20%
Outside your tap

Your estuary is the Langstone Harbour, rated moderate

The Environment Agency rated the Langstone Harbour as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by seagrass and saltmarsh. 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

43

forever-chemical detections in nearby rivers and groundwater

At 3 sites. The highest was PFHxA at 0.04 µg/L, at Hermitage Stream at B2150 Havant - New Road, 6.5 km away, in June 2024. These are river and borehole samples, not tests of your tap water.

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

PO3 in short

Tap water in PO3 (Portsmouth) is supplied by Portsmouth Water in the Portsmouth Central zone and scores 8.4 out of 10, against an England and Wales average of 9.0. 1 of 21 tested substances was close to or over a limit. The latest sample is from 31 December 2024.

  • Nitrite was measured at 0.65 mg/L, 31% over the UK limitIt is the only one of 21 tested substances to go over its limit. See the full results
  • 4th cleanest of 6 areas tested in PortsmouthSquarely mid-table for Portsmouth, between PO2 on 8.7 and PO5 on 8.4. Every area in Portsmouth
  • 0.6 points below the national average of 9Below the typical tested district in the UK, which is worth knowing before you choose a filter. Compare every area

Next door

PO28.7 out of 10PO58.4 out of 10PO48.4 out of 10PO68.5 out of 10PO18.4 out of 10

Questions about PO3 water

Is PO3 tap water safe to drink?

Based on the latest tests, PO3 (Portsmouth) water scores 8.4/10, which is safe. 1 of 21 tested contaminants exceeded recommended levels. Water is supplied by Portsmouth Water.

What contaminants are in PO3 water?

We tested 21 contaminants in PO3 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 PO3?

PO3 (Portsmouth) is supplied by Portsmouth Water. You can view their full profile and compliance data on our supplier page.

Should I use a water filter in PO3?

With 1 contaminant above recommended levels in PO3, 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 PO3 water?

The tap-water tests we hold for PO3 do not include a PFAS result. Environment Agency monitoring found PFAS in 43 river and groundwater samples from 3 sites within 10 km of PO3, the highest being PFHxA at 0.04 µg/L about 6.5 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 PO3?

The Environment Agency rated the Langstone Harbour as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by seagrass and saltmarsh. 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 PO3, which is treated before it reaches homes.

Keep reading

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

River and groundwater readings near PO3

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
pH8.13 pHNone
Temperature17.5 °CNone
Conductivity626 µS/cmNone
Nitrate8 mg/L50 mg/L
Nitrite0.0099 mg/L0.5 mg/L
Phosphate0.024 mg/LNone
Dissolved Oxygen9.51 mg/LNone
Ammonia0.087 mg/L0.5 mg/L
Hardness (as CaCO3)364 mg/LNone
Fluoride0.289 mg/L1.5 mg/L

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Source: Portsmouth 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