Tap water in OX11, South OxfordshireSafe to drink.Very hard.
Supplied by Thames Water. 76 samples, 23 substances, latest on 31 December 2025. Everything is inside the legal limit. One result, nitrite, sits close to the line.
8.7 / 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 253 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
Maximum contaminant removal including PFAS and fluoride
Waterdrop 10UA Under Sink
£70typical price
High-volume under-sink filtration without RO complexity
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What's in a glass of OX11 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 came closest to a limit, at 84% of it. 17 of 19 substances used under a quarter of theirs.
- Nitrite84%
- Nitrate42%
- Trihalomethanes16%
- Nickel15%
- Lead10%
- Bromate10%
- Colour9%
- Cadmium8%
- Fluoride7%
- Mercury7%
- Arsenic7%
- Aluminium6%
- Antimony6%
- Chromium5%
- Boron4%
- Iron3%
- Manganese1%
- Copper1%
- Selenium1%
- Coliform Bacteria none found
- E. coli none found
- Conductivity 539 µS/cm
All 23 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Nitrite | 0.42 mg/L | 0.5 mg/L | 84% |
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Colour | 1.8 mg/L Pt/Co | 20 mg/L Pt/Co | 9% |
| Conductivity | 539 µS/cm | No legal limit | – |
| Fluoride | 0.11 mg/L | 1.5 mg/L | 7% |
| Nitrate | 21 mg/L | 50 mg/L | 42% |
| Hardness (as CaCO3) | 253 mg/L | No legal limit | – |
| Aluminium | 0.0127 mg/L | 0.2 mg/L | 6% |
| Antimony | 0.0003 mg/L | 0.005 mg/L | 6% |
| Arsenic | 0.0007 mg/L | 0.01 mg/L | 7% |
| Boron | 0.04 mg/L | 1 mg/L | 4% |
| Cadmium | 0.0004 mg/L | 0.005 mg/L | 8% |
| Chromium | 0.0025 mg/L | 0.05 mg/L | 5% |
| Copper | 0.02 mg/L | 2 mg/L | 1% |
| Iron | 0.007 mg/L | 0.2 mg/L | 3% |
| Lead | 0.001 mg/L | 0.01 mg/L | 10% |
| Manganese | 0.0006 mg/L | 0.05 mg/L | 1% |
| Mercury | 0.00007 mg/L | 0.001 mg/L | 7% |
| Nickel | 0.003 mg/L | 0.02 mg/L | 15% |
| Selenium | 0.0004 mg/L | 0.04 mg/L | 1% |
| Trihalomethanes | 0.016 mg/L | 0.1 mg/L | 16% |
| Bromate | 0.001 mg/L | 0.01 mg/L | 10% |
253mg of limescale minerals in every litre
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 OX11
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Your river is the Mill Brook and Bradfords Brook system, Wallingford, rated moderate
The Environment Agency rated the Mill Brook and Bradfords Brook system, Wallingford as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by water plants and algae. 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
234
forever-chemical detections in nearby rivers and groundwater
At 7 sites. The highest was PFHxA at 0.05 µg/L, at Moor Ditch Above Didcot STW, 2.1 km away, in November 2023. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Oxford · Which filters remove PFAS · PFAS explained
OX11 in short
Tap water in OX11 (South Oxfordshire) is supplied by Thames Water in the South Oxfordshire Central zone and scores 8.7 out of 10, against an England and Wales average of 9.0. 1 of 23 tested substances was close to or over a limit. The latest sample is from 31 December 2025.
- Nitrite is within its legal limit but flagged, at 84% of the 0.5 mg/L maximumAnything over three quarters of a limit is flagged here as worth watching. It has not gone over. See every reading
- Very hard water at 253 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles in OX11. How hardness is measured
- 3rd cleanest of 10 areas tested in OxfordOnly 2 areas in Oxford scored higher. The best is OX14 on 8.9. Every area in Oxford
Questions about OX11 water
Is OX11 tap water safe to drink?
Based on the latest tests, OX11 (South Oxfordshire) water scores 8.7/10, which is safe. 1 of 23 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.
What contaminants are in OX11 water?
We tested 23 contaminants in OX11 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 OX11?
OX11 (South Oxfordshire) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.
Is OX11 water hard or soft?
Water in OX11 (South Oxfordshire) has a hardness of 253 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 OX11?
With 1 contaminant above recommended levels in OX11, 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 OX11 water?
The tap-water tests we hold for OX11 do not include a PFAS result. Environment Agency monitoring found PFAS in 234 river and groundwater samples from 7 sites within 10 km of OX11, the highest being PFHxA at 0.05 µg/L about 2.1 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 OX11?
The Environment Agency rated the Mill Brook and Bradfords Brook system, Wallingford as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by water plants and algae. 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 OX11, which is treated before it reaches homes.
Keep reading
- Best Filter for PFAS RemovalThe filters with independent certification to remove forever chemicals
- PFAS Forever ChemicalsWhat PFAS are and how to reduce your exposure at home
- 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
PFAS explainedNitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsAll of OxfordUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near OX11
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 OX11.