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2026 Data

UK Postcodes With the Highest Lead Levels

Which UK postcodes have the highest lead levels in drinking water? Data from Environment Agency monitoring.

According to TapWater.uk's analysis of 2,237 UK postcodes, the highest reading was 0.518 mg/L.

0.518

Highest found

0.00234

UK average

0.01

UK limit


Top 50 postcodes

Ranked by lead. Click any postcode for the full breakdown.

1SL6
Slough
0.518 mg/L
2BS11
Bristol, City of
0.49 mg/L
3TN11
Tunbridge Wells
0.3 mg/L
4BS25
North Somerset
0.23 mg/L
5BS9
Bristol, City of
0.1551 mg/L
6DL11
North Yorkshire
0.122 mg/L
7GL13
Stroud
0.0994 mg/L
8GL15
Forest of Dean
0.0652 mg/L
9DA18
Bexley
0.0636 mg/L
10SE16
Southwark
0.0636 mg/L
11YO11
North Yorkshire
0.0422 mg/L
12SO17
Southampton
0.0245 mg/L
13SO18
Southampton
0.0245 mg/L
14DN16
North Lincolnshire
0.0228 mg/L
15EX13
Somerset
0.0186 mg/L
16HR8
Herefordshire, County of
0.018 mg/L
17WD17
Watford
0.0172 mg/L
18WD18
Three Rivers
0.0172 mg/L
19WD19
Hertsmere
0.0172 mg/L
20WD23
Hertsmere
0.0172 mg/L
21WD24
Watford
0.0172 mg/L
22WD25
Hertsmere
0.0172 mg/L
23WD5
Three Rivers
0.0172 mg/L
24BN25
Wealden
0.0166 mg/L
25YO26
North Yorkshire
0.0151 mg/L
26YO30
North Yorkshire
0.0151 mg/L
27YO21
North Yorkshire
0.0129 mg/L
28TS15
North Yorkshire
0.0125 mg/L
29DL12
North Yorkshire
0.0124 mg/L
30L34
St. Helens
0.0124 mg/L
31L35
St. Helens
0.0124 mg/L
32SS16
Thurrock
0.0117 mg/L
33ME16
Maidstone
0.0113 mg/L
34MK18
Cherwell
0.0109 mg/L
35CR4
Sutton
0.0105 mg/L
36SW4
Wandsworth
0.0105 mg/L
37LU3
Central Bedfordshire
0.01 mg/L
38LU4
Central Bedfordshire
0.01 mg/L
39LU5
Central Bedfordshire
0.01 mg/L
40CB22
Cambridge
0.009 mg/L
41NP19
Newport
0.0086 mg/L
42DL14
County Durham
0.00858 mg/L
43CB11
Uttlesford
0.0078 mg/L
44CA1
Cumberland
0.00774 mg/L
45CA2
Cumberland
0.00774 mg/L
46CA3
Cumberland
0.00774 mg/L
47DL2
North Yorkshire
0.00768 mg/L
48RG10
Wokingham
0.0076 mg/L
49RG22
Basingstoke and Deane
0.0076 mg/L
50RG23
Basingstoke and Deane
0.0076 mg/L

Based on Environment Agency water quality monitoring. Values show the most recent lead reading for each postcode district.


What this means

Lead is a toxic heavy metal with no safe level of exposure. Even low concentrations can cause neurological damage, particularly in children. The UK reduced its legal limit from 0.025 mg/L to 0.01 mg/L in 2013 to align with WHO guidelines. Most lead contamination comes from old lead pipes rather than the water supply itself.


How to protect yourself

A reverse osmosis system or activated carbon filter certified to NSF/ANSI 53 can remove over 99% of lead from drinking water.


Check your postcode

See the full water quality report for your area, including all tested contaminants and personalised filter recommendations.


Frequently asked questions

What is the safe limit for lead in drinking water?

The UK legal limit for lead in drinking water is 0.01 mg/L (10 micrograms per litre). The WHO recommends keeping lead as low as reasonably practicable, as there is no known safe level of exposure to lead.

Why is lead found in UK tap water?

Lead in UK tap water typically comes from old lead service pipes connecting properties to the water main. Homes built before 1970 are most likely to have lead pipes. Water companies treat water to reduce lead dissolving from pipes, but replacement is the only permanent solution.

How can I reduce lead in my tap water?

You can reduce lead exposure by running the tap for 30 seconds before use (especially in the morning), using a water filter certified to remove lead (such as a reverse osmosis system), or arranging for your water company to replace lead service pipes.


More rankings

View all rankings

Data from the Environment Agency Water Quality Archive and water company testing. Rankings compiled by TapWater.uk from 2,237 postcode districts. See our methodology for how scores are calculated.