Lead in UK drinking water: check your pipes, test your tap

Where lead in tap water comes from

Lead gets into tap water on the way to your tap, not at the treatment works. Scotland's regulator says “Water does not contain lead when it leaves the treatment works.” DWQR The DWI explains where it comes from: “Before 1970, lead pipework was commonly used to connect properties to the mains water network.” DWI

“The use of lead pipes has since been banned, however many older properties that have not been modernised are likely to have lead pipework underground and/or inside the building.”

Once it is there, it gets into the water: “Lead from pipework can dissolve into the water whilst it stands in the pipe.” DWI Water companies reduce this: “Where a risk of lead exists, water companies treat the water with orthophosphate to reduce the problem significantly.” DWI But “None the less, particles of lead may build up in these older pipes and intermittently appear in tap water.” DWI

How much lead ends up in a glass varies. The DWI lists the time water stands in the pipe, the pipe's condition, the season (“more lead will dissolve during the summer and autumn months” DWI) and hardness: “harder water tends to form a protective scale over the surface of the pipe which can reduce the concentration of lead in the water.” DWI

Who owns which pipe

Two owners share the pipes between the street and your kitchen tap: the water company and the property owner. Who owns which part decides who replaces it. Tap a number on the diagram at the top of the page, or read the four points below.

In Scotland the split is the same. Scottish Water “has responsibility for the part of the service pipe and connection within the street - the Communication pipe.” DWQR

How to spot a lead pipe

The DWI's rule of thumb is the age of the home DWI: built “before 1970 – it may have lead pipes”; built “after 1970 – it is unlikely to have lead pipes”. If you are not sure, you can look.

The DWI's check

Find your inside stop tap, where the water first comes into the home. The DWI says “This may be in or behind the cupboards in your kitchen or a downstairs toilet.” DWI

“Unpainted lead pipes appear dull grey and often have a swollen joint next to the tap.” DWI “The metal is soft and, if gently scraped with a coin, you will see the shiny, silver-coloured metal beneath.” DWI And take care: “Wear disposable gloves while you do this and be careful not to breathe in any dust.” DWI

Other pipes you might find, in the DWI's words DWI:

• “copper – bright, hard and dull brown”
• “iron – dark, very hard and may be rusty”
• “plastic – typically blue but if older it may be grey or black.”

A copper pipe at the stop tap doesn't clear the pipe under the garden. The DWI's point is that older homes may have lead “underground and/or inside the building.” DWI A test at the kitchen tap covers the whole route.

Why lead matters

The DWI says “Lead can build up in the body and it is recommended that exposure to lead minimised as far as possible.” DWI

“Those at particular risk are infants (including unborn babies) and children because lead can have an adverse impact on mental development.”

For adults, “it may impair kidney, heart and circulatory health.” DWI Scotland's regulator says “Lead is toxic and where it does exist, the people most at risk are children, babies and pregnant women as it impairs development of the child.” DWQR

There is a legal limit at the tap. In Scotland's regulator's words, “All drinking water is required to meet the standard for lead (10µg/l) that came into force in December 2013.” DWQR Older pipes are why some taps don't: “Part, or all, of the service pipes connecting the water main in the street to the kitchen tap in older properties may be made of lead, and consequently the water may not always meet the standard at the consumer’s tap.” DWQR

Cut your exposure today

If you have, or might have, lead pipes, there is a simple habit that helps straight away. The DWI's advice: “For drinking and cooking, run the tap to clear any water that has been standing in the pipework for while, for example, overnight.” DWI “A washing up bowl full is normally enough to clear the pipe of standing water, although if you have long service pipe you may need to run the tap for longer.” DWI

It needn't be wasted: “This need not be wasted but can be used to water plants or for something other than drinking or cooking.” DWQR Running the tap is a stopgap, though. “This short-term measure will protect you and your family, but if there are lead pipes or another source of lead present, these should be replaced as soon as possible.” DWI

1. 1. Run the tap first. Clear standing water before drinking or cooking, as above, until the pipes are replaced.
2. 2. Ask your water company to test. “If you suspect that your home has lead pipes you can ask your water company to test the water at your kitchen tap.” DWI
3. 3. Plan the replacement. “Ultimately, the only certain way to reduce exposure to lead is to remove all lead pipework from the property.” DWQR See chapter 07.

Ways to test: home, water company or lab

There are three ways to find out, and they answer slightly different questions.

We suggest testing at the kitchen tap, because that is the water you drink. Follow your kit's instructions on when to take the sample: the DWI lists “How long the water has been standing in the pipe” DWI as one of the things that changes how much lead is in it.