Lead almost never comes from the water source — it comes from old pipes. The UK legal limit is 10 µg/L, tightening to 5 µg/L in 2036. Here is the national picture from our data, and what it means for your postcode.
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Lead is almost never present in the water leaving a treatment works. It gets into tap water when water sits in contact with old lead pipes and lead-soldered joints inside the supply pipe or a property’s own plumbing. The longer the water stands still — overnight, or while you are out — the more lead can dissolve into it. That is why the same street can show very different lead at the tap depending on each house’s pipework, and why lead is really a plumbing issue rather than a water-source issue.
The UK legal limit for lead in drinking water is 10 micrograms per litre (µg/L), reduced from 25 µg/L in 2013. This matches the World Health Organization guideline, although the WHO is clear that there is no level of lead exposure known to be completely without effect. The limit is scheduled to tighten further to 5 µg/L in 2036, which will require more lead pipe removal across the country.
Our lead pipe risk model scores roughly 1.5 million UK postcodes using housing age and plumbing indicators. On that model, about 30% of all scored postcodes (including zone-only fallbacks) fall in the High likelihood band for some lead pipework and a further 25% are Medium — so more than half of UK postcodes carry an elevated likelihood, driven almost entirely by homes built before 1970. On the narrower set of postcodes that have property-level EPC evidence, the High share is 34%; the two figures use different denominators and both are correct. This is a likelihood based on local housing, not a measurement of any individual home. You can read how the bands are calculated in the model methodology.
Alongside the likelihood model, we hold the measured lead figures reported for supply zones. Of 1,574 zones that report a lead result, the mean is comfortably below the 10 µg/L limit in almost every zone — only 24 zones show a mean at or above 5 µg/L. A small number (about 45 zones) recorded an individual maximum at or above the 10 µg/L limit, which reflects lead plumbing inside specific older properties rather than the mains supply. Enter your postcode above to see the measured mean for your own zone.
Run the cold tap for a couple of minutes first thing in the morning before drinking or cooking; always draw drinking and cooking water from the cold tap, never the hot; and if you have or suspect lead pipes, fit a filter certified to NSF/ANSI 53 for lead — a reverse-osmosis system or a certified solid carbon block. The permanent fix is pipe replacement. Start by checking whether your house has lead pipes, then the likely replacement cost, and read the full lead pipes guide.
Water leaving UK treatment works contains essentially no lead. Lead enters tap water only where it passes through old lead pipes or lead-soldered joints in a property's plumbing. Of 1,574 supply zones reporting lead, almost all have a mean below the 10 µg/L legal limit; a small number of individual readings exceed it because of lead plumbing in specific older homes.
The UK limit is 10 micrograms per litre (µg/L), reduced from 25 µg/L in 2013 and scheduled to tighten to 5 µg/L in 2036. It matches the WHO guideline, though the WHO notes there is no exposure level proven completely without effect.
On our postcode-level model of around 1.5 million postcodes, about 30% of all scored postcodes fall in the High likelihood band for some lead pipework and a further 25% are Medium — so more than half of UK postcodes carry an elevated likelihood, almost entirely because of homes built before 1970.
Flush the cold tap for a couple of minutes each morning before drinking or cooking, always use the cold tap for drinking water, and fit a filter certified to NSF/ANSI 53 for lead, such as a reverse-osmosis system. The permanent solution is replacing the lead pipework.
Lead at the tap depends on your own property's pipes more than your area. Enter your postcode to see the measured mean lead level for your supply zone, and use the lead pipe risk checker to estimate the likelihood of lead pipework for your address.