How to build (or refresh) your knowledge of environmental water quality
Published on: 23 Oct 2024
Read moreDrinking water can be a significant source of lead exposure, which is known for its detrimental health effects. In the UK, lead pipes were commonly used before 1970 to connect properties to the mains water network. Although their use has been banned since then, it is likely that many older properties still have underground or internal lead pipes, contributing to ongoing concerns about lead contamination in drinking water. The World Health Organization (WHO) identifies lead as a major public health concern, associated with issues from reduced IQ in children to elevated blood pressure in adults; even minor concentrations of lead (e.g., 3.5 µg/dL)1 have significant health impacts. To meet stricter lead concentration standards, orthophosphate dosing has proven effective in reducing lead levels in drinking water. However, utilities increasingly prioritise permanent solutions, such as replacing lead pipes with safer materials, over relying solely on corrosion control measures.
Several approaches exist for finding lead pipes in water systems. Direct methods, such as visual inspection through excavation, offer accuracy but are labour intensive and financially impractical given the estimated 6 million lead pipes in the UK. Alternative methods such as scratch and magnetic tests or lead swabs offer less invasive options but lack assurance of detecting lead throughout the entire service line, without needing public engagement. Indirect methodologies, including online inventories using Geographic Information Systems (GIS) and machine learning, rely on historical data to estimate the probability of lead pipe presence. However, they cannot guarantee precise location, as they depend on the reliability of historical records - thereby introducing uncertainty. Water sampling techniques detect lead presence, but they cannot distinguish if lead originated from pipes, solder, or fixtures elsewhere in the plumbing system.
Given the current situation, there is an urgent demand for direct non-intrusive technologies to precisely locate lead pipes in water systems. Ongoing technology development and prototype advancements, each with distinct strengths and limitations, necessitate a thorough understanding to effectively support lead pipe renewal initiatives.
WRc is currently collaborating with research institutions, universities, and technology suppliers worldwide to review the development status of lead pipe identification technologies. Our assessment evaluates both emerging and established solutions, focusing on non-invasive methods to enhance lead pipe tracking and mitigate associated risks.
Acoustic screening (stress wave propagation) stands out as an advanced technology capable of identifying lead materials across the entire length of a service line, including communication and customer-side pipes. This method relies on unique acoustic properties of materials, with specific velocity measurements of acoustic waves used for material identification. It is non-disruptive and eliminates the need for excavation. While market options are limited, ongoing research projects aim to introduce competition, offering diverse solutions tailored to water utilities' needs.
Electric resistivity is gaining traction, particularly in the United States. This method leverages the principle of different materials having distinct electrical conductivities. It measures the electrical resistance when a current passes through a material, providing distinct values for different metals. Although it has a strong history of effectively detecting lead materials, caution is necessary due to its invasive nature.
The use of Ground Penetrating Radar (GPR) integrated with Cable Locators (EM) is significant for non-invasive metallic pipe identification. It aids material diagnosis through hyperbolic analysis, with lighter shades indicating plastic and darker shades suggesting metal. Additionally, pipe diameter estimation can assist in lead pipe determination. Further refinement of GPRs for material discrimination, including analysis of backscattered data, is essential.
As part of the current Portfolio project 'Lead Identification Technology Review', WRc is conducting an in-house assessment of the most promising lead identification technologies available to evaluate their accuracy, non-invasiveness and practical applicability within the UK context. Through blind tests, in collaboration with technology suppliers using our state-of-the-art lead pipes rig, we aim to understand the strengths and limitations of these technologies in real-world settings. This understanding will not only drive research improvements to tackle such a challenging topic in the water sector, but also support water companies in making informed decisions for their lead renewal programmes. Ultimately, it will foster a transition towards lead-free water systems and the safeguarding of public health.
References
1 - Centers for Disease Control and Prevention (2022). CDC updates blood lead reference value | Lead | CDC. [online] www.cdc.gov. Available here.