2026 Data
UK Postcodes With the Highest Nitrate Levels
Nitrate levels by UK postcode. Data from Environment Agency and water company testing.
According to TapWater.uk's analysis of 2,245 UK postcodes, the highest reading was 45.7 mg/L.
45.7
Highest found
15.5
UK average
50
UK limit
Top 50 postcodes
Ranked by nitrate. Click any postcode for the full breakdown.
Based on Environment Agency water quality monitoring. Values show the most recent nitrate reading for each postcode district.
What this means
Nitrate is one of the most common contaminants in UK groundwater, primarily from agricultural fertiliser use. The UK legal limit is 50 mg/L, matching WHO guidelines. Water companies blend high-nitrate sources with cleaner supplies to keep levels within limits, but some areas consistently test near the threshold.
How to protect yourself
Reverse osmosis is the most effective method for removing nitrate. Standard carbon jug filters do not remove nitrate effectively.
Check your postcode
See the full water quality report for your area, including all tested contaminants and personalised filter recommendations.
Frequently asked questions
What causes high nitrate levels in UK water?
High nitrate levels are primarily caused by agricultural fertiliser runoff and livestock waste entering water sources. Areas with intensive farming, particularly in eastern England, tend to have the highest nitrate concentrations.
Is nitrate in drinking water dangerous?
At levels above 50 mg/L, nitrate can pose health risks, particularly for bottle-fed infants under 6 months (causing 'blue baby syndrome'). For most adults, nitrate at typical UK levels is not considered dangerous, though some studies link long-term exposure to certain cancers.
How can I remove nitrate from tap water?
Standard carbon filters and boiling do not remove nitrate. Reverse osmosis systems or ion exchange filters are effective at reducing nitrate levels. If you have a baby under 6 months and live in a high-nitrate area, consider using bottled water for formula.
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