What do we do about lead water pipes?

To comply with the US EPA Lead and Copper Rule Revision, all drinking water systems with lead service lines face a major decision: optimize treatment or begin a program to replace remaining lead service lines. Even systems without lead service lines could come under both regulatory and public scrutiny based on requirements for “find and fix” pipe replacement, mandatory testing for schools and childcare facilities or exceedance of the new 10 parts per billion (ppb) trigger level.

Under the new rule the need to replace lead service lines could be triggered in multiple ways:

• An exceedance of the action level (90th percentile Pb > 15 ppb)
• Trigger level (90th percentile Pb > 10 ppb)
• “Find and fix” hits (any sample location Pb > 15 ppb)
• Public pressure from hits in schools
• Modified sample procedures under the new rule can increase water sample lead concentrations for systems currently in compliance

Replacing the US EPA estimated 6 to 10 million lead service lines in the US is one solution, but it comes with a lengthy schedule, considerable cost, operational resources, and disruptions to the community and traffic. Lead pipe replacement can result in disruption of scales in any remaining premise pipe and actually increase tap lead concentrations in the short term after a replacement is made.

Is there an alternative to replacing all lead service lines or given the lengthy schedule, provides communities with a level of comfort until all lead service lines can be replaced? Although orthophosphate is routinely used in the U.S for corrosion control treatment, the use of it in the United Kingdom (UK) to optimize treatment where lead service lines are also common, offers an interesting perspective on how to meet the new requirements in the US.

In the UK, about 40% of properties are supplied via a lead pipe. Water companies in England and Wales are required to use orthophosphate unless an alternate approach can be demonstrated to be as effective. As a result, 95% of public water supplies in the UK use orthophosphate for lead control.^[i]The concentration of orthophosphate used in the UK varies, most typically between 3.0 and 4.5 mg/L (PO4), which is generally two to three times higher than dosed in the US, where values are typically 0.6 to 3.0 mg/L (PO4).^[ii] Seeing these results at the much higher levels used in the UK demonstrates the success we would also expect to see in the US.

Review of data from 14,000 annual lead analyses in Northwest England provides a major opportunity to quantify the lead risk and the effectiveness of orthophosphate treatment. In this region, about a third of properties have lead service pipes. This data clearly shows substantial improvements have occurred over the 10-year period in which orthophosphate dosing was introduced and then gradually increased.

The following figure is a plot of the lead 90th percentile concentration versus orthophosphate and confirms the expected trend of reducing lead concentrations with increasing orthophosphate concentration.^[iii] The graph demonstrates it is possible in systems with lead service lines to maintain 90th percentile at 5 ppb or less provided sufficient orthophosphate is used. It should be noted the cost of orthophosphate will usually be a relatively small percentage of overall treatment costs. Some may object to this approach because it increases the phosphate dosage at wastewater treatment facilities. While this is true, an increase in wastewater influent phosphorous does not necessarily equate to an increase in treated water phosphorous, provided treatment is adjusted.

Even with optimized treatment some water systems may decide the best approach is a gradual replacement of lead services lines, given public pressure, uncertain future regulatory requirements, long term liability and the fact all lead pipes are relatively old. In the meantime, an optimized corrosion control treatment approach could buy the system more time to replace lead service lines, improve customer relations, and decrease regulatory difficulties.

Engaging partners that combine regulatory understanding with deep water knowledge will be imperative for successfully meeting environmental requirements, while balancing a water supplier’s business goals. Our experienced professionals understand all facets of the Lead and Copper Rules Revisions, track the regulatory changes, and offer technical services to plan for addressing requirements, and meeting and maintaining compliance strategies. Our global water network provides comprehensive and innovative solutions in water treatment. We are committed to applying our knowledge of municipal operations and experience in utility management and water treatment services to ensure compliance while meeting our clients’ business goals and growth plans.

References:

[i] Colin R. Hayes, “UK experience in the monitoring and control of lead in drinking water” Journal of Water and Health | 10.3 | 2012

[ii] Brown Et al | 105:5 • “Strategies for assessing optimized corrosion control treatment of lead and copper” Journal AWWA | May 2013

[iii] Cardew P.T. “Measuring the benefit of orthophosphate treatment on lead in drinking water” Journal of Water and Health | 07.1 | 2009

https://www.epa.gov/sites/production/files/2016-03/documents/occtmarch2016.pdf