Tap water in NN4, West NorthamptonshireSafe to drink.Very hard.
Supplied by Anglian Water. 1,211 samples, 19 substances, latest on 23 December 2024. Everything is inside the legal limit, and nothing comes close to it.
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 262 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
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 NN4 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 36% of it. 15 of 16 substances used under a quarter of theirs.
- Nitrate36%
- Fluoride17%
- Trihalomethanes14%
- Nickel12%
- Iron12%
- Nitrite10%
- Antimony6%
- Aluminium6%
- Manganese6%
- Turbidity5%
- Arsenic3%
- Selenium2%
- Lead2%
- Chromium2%
- Copper2%
- Cadmium<1%
- Coliform Bacteria none found
- E. coli none found
- Conductivity 563 µS/cm
All 19 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Nitrate | 17.8 mg/L | 50 mg/L | 36% |
| Nitrite | 0.05 mg/L | 0.5 mg/L | 10% |
| Aluminium | 0.012 mg/L | 0.2 mg/L | 6% |
| Copper | 0.03 mg/L | 2 mg/L | 2% |
| Nickel | 0.00243 mg/L | 0.02 mg/L | 12% |
| Lead | 0.00016 mg/L | 0.01 mg/L | 2% |
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Conductivity | 563 µS/cm | No legal limit | – |
| Trihalomethanes | 0.0142 mg/L | 0.1 mg/L | 14% |
| Fluoride | 0.26 mg/L | 1.5 mg/L | 17% |
| Turbidity | 0.21 NTU | 4 NTU | 5% |
| Iron | 0.024 mg/L | 0.2 mg/L | 12% |
| Manganese | 0.003 mg/L | 0.05 mg/L | 6% |
| Arsenic | 0.00031 mg/L | 0.01 mg/L | 3% |
| Cadmium | 0.00002 mg/L | 0.005 mg/L | <1% |
| Chromium | 0.00076 mg/L | 0.05 mg/L | 2% |
| Antimony | 0.00032 mg/L | 0.005 mg/L | 6% |
| Selenium | 0.00072 mg/L | 0.04 mg/L | 2% |
262mg 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 NN4
Leave your details and we will email you when we can match you with installers who cover NN4. No obligation.
Request a free assessment and we'll come back to you with local installer options for your area.
100%
free, no obligation
shared only with your consent
Your river is the Wootton Brook, rated poor
The Environment Agency rated the Wootton Brook as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by water plants and algae, dissolved oxygen and phosphate. 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
98
forever-chemical detections in nearby rivers and groundwater
At 5 sites. The highest was 6:2 FTSA at 0.07 µg/L, at Billing Bk.lt.billing Rd.br.northampton, 6.6 km away, in August 2025. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Northampton · Which filters remove PFAS · PFAS explained
NN4 in short
Tap water in NN4 (West Northamptonshire) is supplied by Anglian Water in the West Northamptonshire Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 19 tested substances came close to a limit. The latest sample is from 23 December 2024.
- Very hard water at 262 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles in NN4. How hardness is measured
- 5th cleanest of 12 areas tested in NorthamptonSquarely mid-table for Northampton, between NN11 on 9.4 and NN12 on 8.9. Every area in Northampton
- PFAS found at 5 monitoring sites within 10 kmThose are river and groundwater samples, not tap water. The highest was 6:2 FTSA about 6.6 km away. What was measured
Questions about NN4 water
Is NN4 tap water safe to drink?
Based on the latest tests, NN4 (West Northamptonshire) water scores 9.3/10, which is safe. 0 of 19 tested contaminants exceeded recommended levels. Water is supplied by Anglian Water.
What contaminants are in NN4 water?
We tested 19 contaminants in NN4 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 NN4?
NN4 (West Northamptonshire) is supplied by Anglian Water. You can view their full profile and compliance data on our supplier page.
Is NN4 water hard or soft?
Water in NN4 (West Northamptonshire) has a hardness of 262 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 NN4?
NN4 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 NN4 water?
The tap-water tests we hold for NN4 do not include a PFAS result. Environment Agency monitoring found PFAS in 98 river and groundwater samples from 5 sites within 10 km of NN4, the highest being 6:2 FTSA at 0.07 µg/L about 6.6 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 NN4?
The Environment Agency rated the Wootton Brook as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by water plants and algae, dissolved oxygen and phosphate. 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 NN4, 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?
- 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 explainedHow to test your waterBest water filtersFilter shower headsWater testing kitsAll of NorthamptonUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near NN4
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.
| Substance | Reading | Drinking water limit |
|---|---|---|
| Nickel | 0.024 mg/L | 0.02 mg/L |
| Turbidity | 5 NTU | 4 NTU |
| Manganese | 0.0717 mg/L | 0.05 mg/L |
| pH | 8.16 pH | None |
| Temperature | 16.2 °C | None |
| Conductivity | 889 µS/cm | None |
| Nitrate | 16 mg/L | 50 mg/L |
| Nitrite | 0.014 mg/L | 0.5 mg/L |
| Phosphate | 0.053 mg/L | None |
| Dissolved Oxygen | 9.3 mg/L | None |
| Ammonia | 0.066 mg/L | 0.5 mg/L |
| Cadmium | 0.000012 mg/L | 0.005 mg/L |
| Lead | 0 mg/L | 0.01 mg/L |
| Chromium | 0.00105 mg/L | 0.05 mg/L |
| Copper | 0.00476 mg/L | 2 mg/L |
| Zinc | 0.0362 mg/L | None |
| Arsenic | 0.0011 mg/L | 0.01 mg/L |
Get alerts for your area
We'll email you when water quality data changes for NN4.