Lead enters tap water from old pipes inside a property, not from the mains. On our model of 1.5 million UK postcodes, 30% of all scored postcodes (including zone-only fallbacks) fall in the High likelihood band for lead pipework and a further 25% are Medium — driven almost entirely by homes built before 1970.

Lead is no longer added to anything in a modern water system — but it is still present in the pipes of millions of older homes. Because lead enters tap water from a property's own plumbing rather than the mains, it is one of the few water-quality issues that depends on your individual house, not just your area.

How widespread is it?

Our lead pipe risk model scores around 1.5 million UK postcodes using housing age and plumbing indicators. On that model:

  • 30% of all scored postcodes (including zone-only fallbacks) fall in the High likelihood band for some lead pipework;
  • 25% are Medium;
  • the remaining 45% are Low.

In other words, more than half of all scored postcodes carry an elevated likelihood of some lead pipework — almost entirely because of homes built before 1970, when lead was the standard material for supply pipes. On the narrower set of postcodes with property-level EPC evidence, the High share is 34%; both figures are correct on their own denominator — see the methodology.

What the measured data shows

Alongside the model we hold measured lead figures for supply zones. Of 1,574 zones that report lead, the mean is below the 10 µg/l legal limit in almost every one — only 24 zones show a mean at or above 5 µg/l. A small number, around 45 zones, recorded an individual maximum at or above the limit, which reflects lead plumbing inside specific older properties rather than the mains supply.

The limit is about to tighten

The UK legal limit for lead in drinking water is 10 micrograms per litre, already reduced from 25 µg/l in 2013, and it is scheduled to fall further to 5 µg/l in 2036. That will require a great deal more lead pipe removal across the country over the next decade.

What you can do

If your home predates 1970, it is worth finding out. Our guide explains how to check whether your house has lead pipes using the scratch and magnet tests, and you can estimate the likelihood for your address with the free lead pipe risk checker. If you find lead, see the typical replacement costs and the full lead pipes guide. In the meantime, running the cold tap for a couple of minutes each morning and using a filter certified to NSF/ANSI 53 both reduce exposure.

Source: MyTapWater lead pipe risk model (v1.0, ~1.5M postcodes) and measured lead data from official UK water-company reporting (2025).