Tap water in BN9, LewesSafe to drink.
Supplied by Southern Water. 3,352 samples, 22 substances, latest on 2 April 2026. Everything is inside the legal limit, and nothing comes close to it.
9.3 / 10
The tank is as full as the score.
What to do about it
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
BRITA Marella XL + MAXTRA PRO
£25typical price
Basic chlorine and taste improvement on a budget
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What's in a glass of BN9 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 67% of it. 17 of 18 substances used under a quarter of theirs.
- Nitrate67%
- Trihalomethanes15%
- Colour15%
- Nickel8%
- Aluminium6%
- Ammonia5%
- Iron5%
- Lead4%
- Antimony4%
- Manganese4%
- Turbidity3%
- Cadmium2%
- Chromium2%
- Arsenic1%
- Bromate1%
- Nitrite<1%
- Selenium<1%
- Copper<1%
- Coliform Bacteria none found
- E. coli none found
- pH 7.7 pH
- Conductivity 487 µS/cm
All 22 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Aluminium | 0.0113 mg/L | 0.2 mg/L | 6% |
| Iron | 0.00928 mg/L | 0.2 mg/L | 5% |
| Manganese | 0.00178 mg/L | 0.05 mg/L | 4% |
| Coliform Bacteria | 0 count/100ml | Must be zero | None found |
| E. coli | 0 count/100ml | Must be zero | None found |
| Colour | 3 mg/L Pt/Co | 20 mg/L Pt/Co | 15% |
| Turbidity | 0.13 NTU | 4 NTU | 3% |
| pH | 7.7 pH | No legal limit | – |
| Nitrate | 33.7 mg/L | 50 mg/L | 67% |
| Nitrite | 0.004 mg/L | 0.5 mg/L | <1% |
| Lead | 0.0004 mg/L | 0.01 mg/L | 4% |
| Trihalomethanes | 0.0152 mg/L | 0.1 mg/L | 15% |
| Conductivity | 487 µS/cm | No legal limit | – |
| Bromate | 0.00013 mg/L | 0.01 mg/L | 1% |
| Ammonia | 0.025 mg/L | 0.5 mg/L | 5% |
| Copper | 0.0146 mg/L | 2 mg/L | <1% |
| Arsenic | 0.00015 mg/L | 0.01 mg/L | 1% |
| Cadmium | 0.00012 mg/L | 0.005 mg/L | 2% |
| Chromium | 0.001 mg/L | 0.05 mg/L | 2% |
| Nickel | 0.00168 mg/L | 0.02 mg/L | 8% |
| Antimony | 0.0002 mg/L | 0.005 mg/L | 4% |
| Selenium | 0.00032 mg/L | 0.04 mg/L | <1% |
Your estuary is the Ouse, rated moderate
The Environment Agency rated the Ouse 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
BN9 in short
Tap water in BN9 (Lewes) is supplied by Southern Water in the Lewes Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 22 tested substances came close to a limit. The latest sample is from 2 April 2026.
- Nitrate is the reading closest to its limit, at 67% of the 50 mg/L maximumIt passed with room to spare, and everything else tested sat further below its limit. See every reading
- 3rd cleanest of 5 areas tested in LewesSquarely mid-table for Lewes, between BN10 on 9.3 and BN25 on 9.
- Scores higher than 2 of 4 neighbouring districtsWater here is typical for the immediate area, which usually means the same treatment works and the same supply zone.
Questions about BN9 water
Is BN9 tap water safe to drink?
Based on the latest tests, BN9 (Lewes) water scores 9.3/10, which is safe. 0 of 22 tested contaminants exceeded recommended levels. Water is supplied by Southern Water.
What contaminants are in BN9 water?
We tested 22 contaminants in BN9 water. None exceeded recommended safe levels.
Who supplies water in BN9?
BN9 (Lewes) 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 BN9?
BN9 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 BN9 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for BN9, and the Environment Agency has no PFAS detections in rivers or groundwater within 10 km of it. That reflects where sampling has happened as much as the water itself.
How clean is the estuary near BN9?
The Environment Agency rated the Ouse 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 BN9, which is treated before it reaches homes.
Keep reading
- Is UK Tap Water Safe?Everything you need to know about tap water safety in the UK
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- How to Test Your Tap WaterFrom DIY strips to professional lab analysis
- Best Water Filter Jug UKBRITA vs ZeroWater vs the rest, tested against real data
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River and groundwater readings near BN9
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 BN9.