Lead in private water supplies
Sources of lead
Lead used to be common in the environment due to its widespread historic use in petrol, paint and water pipes. Before 1970, lead pipework was commonly used in domestic distribution systems and to connect properties to an incoming supply, be it a public or private supply. The use of lead pipes has since been banned; however, many older properties that have not been modernised might still have lead pipework underground and/or inside a building.
Risk of lead in private water supplies
Irrespective of the age of a premises or its domestic distribution system, the infrastructure between the source and a premise served by a private supply may also present lead risks from pipes and/or the supply source. The presence of lead in the latter can be naturally occurring or the result of historical lead mining where these industries once operated. This tends to be in rural areas where private supplies are most prevalent. Another potential source of lead is through the continued use of lead solder in drinking water systems.
This presents a notable risk where a supply is decades old (as many are) and it has not been inspected, maintained (for example, flushed), or tested for lead over an extensive duration. This may lead to long exposure periods to lead where it is present in the supply, where the risk has not been recognised. This oversight might be because the owner/user(s) has never suspected or considered a lead risk, or the supply is exempt from the regulatory testing and risk assessment requirements that were implemented in 2010.
Mains water supplies operated by water companies are often conditioned with phosphate to reduce the amount of lead dissolving into the water supply at consumer properties. However, this phosphate dosing is highly unlikely to be equipped in private water supply networks.
Does lead in a private supply present a danger to health?
Lead can build up in the body and it is recommended by health professionals that exposure to it is minimised as far as possible. Infants (including unborn babies) and children are particularly at risk because lead can have an adverse impact on mental development. Lead may also be factor in behavioural problems. In adults it may impair kidney, heart and circulatory health. In 2010, the World Health Organization (WHO) concluded that there is “no apparent health-based threshold for lead”, this means that there is no safe level of lead.
The risk of lead in private water supplies should be considered on a case-by-case basis where it is suspected or detected. The local authority is the regulator for private water supplies and should be the first point of contact for any concerns, or should you wish a private supply to be checked for lead.
How is the risk of lead in private water supplies determined?
Local authorities must take account of any potential or actual lead risk as part of a regulatory risk assessment, which it must review every five years subsequently. This applies to all shared, public and commercial supplies. In Wales, this also includes all supplies provided as part of a tenancy agreement. The frequency of testing for lead on these supply types is carried out according to the size of the supply.
For small, shared supplies (<10 m3 per day), lead is only tested where it is considered a risk.
Local authorities must investigate the cause when lead is suspected and/or detected above the regulatory standard of 10 µg/L on any private supply type. The local authority should seek health advice from the UKHSA or Public Health Wales (as applicable), as part of its investigations.
Consumers on private supplies that serve a single dwelling in isolation are not subject to mandatory risk assessments or testing for lead, although a local authority may carry out testing on these supplies at its own discretion and cost. However, if an owner or occupier of a premise on a private supply has concerns about lead or they wish to have their supply assessed for lead at any time, they should contact the local authority for advice or to facilitate a risk assessment and/or testing. Local authorities are duty bound to provide these services when requested to do so by the premise owner or occupier, where the supply serves only a single dwelling.
When sampling is conducted at a premises, local authority samplers will take samples to test for plumbing metals including lead prior to taking any other samples. As the primary source of lead in drinking water is due to pipes and fittings, this ‘first draw’ sample enhances the likelihood of flagging the presence of lead.
What if lead is found or suspected in a private water supply?
The local authority must inform, offer advice and act in accordance with the current Private Water Supplies Regulations (England or Wales as applicable) where lead is detected or suspected in a private supply. The local authority must investigate the cause where this is the case. The outcome and any subsequent actions will depend on (a) whether the cause was due to the distribution system within a domestic premises, or (b) the wider supply system or the catchment.
The local authority is compelled to use its powers of enforcement to require a suitable remedy to mitigate the lead risk where:
- The cause is due to the distribution system (all pipes and fittings) within a domestic premises, where the water is made available to the public, and/or
- the cause is not due to the distribution system with a domestic premise
This is because lead presents a potential danger to human health. The local authority is duty bound to enforce under these circumstances.
Who is responsible for the pipework on a private water supply?
The plumbing (all pipes and fittings) inside any premise (whether commercial, public or domestic) that is served by a private water supply is usually the responsibility of the property owner.
Where a private supply is shared, the ownership/responsibility for all other pipes and fittings that do not constitute a distribution system within a domestic premises, will be case specific. Anyone that constitutes a relevant person as defined in section 80 of the Water Industry Act 1991 could potentially be served an enforcement notice to remediate a lead risk where the local authority has establish a lead risk on any private supply.
Sometimes the ownership of pipes, fittings and other assets on shared supplies is not known, or it is disputed between relevant persons. This can result in disagreements over responsibilities and the apportion of costs, causing delays to remediation. This is likely to extenuate the risk. For this reason, relevant persons are advised to proactively establish local agreements, preferably legal binding, to prevent this.
Replacing Lead Pipework
Anyone planning the replacement of pipework to a premise is advised to employ a qualified plumber to carry out the work, for example one who is accredited through the WaterSafe scheme. Refer to the WaterSafe website and see also our Advice Leaflet for finding a plumber.
Further reading
Additional advice and information on lead in drinking water can be found on the Inspectorate’s general lead page and on this podcast.
The WHO has published a technical brief titled ‘Lead in drinking-water’.