How Does Lead Get into Drinking Water? How Can Local Municipalities Remove It?
In light of the Flint water crisis—when, in 2014, Flint officials changed the city’s water source from the Detroit Water and Sewerage Department to the Flint River, leaching unsafe levels of lead into the public water supply due to improper treatment—many people are wondering if the same thing could happen in their own communities and homes.
Some folks believe this could be the tip of the iceberg, and that with older piping carrying municipal water to local houses, schools, and workplaces, more stories like Flint will continue to surface. Because of this, municipal water distributors need to increase awareness of these developments, keep on top of new rules and regulations for drinking water distribution, and be sure to explore the many treatment options available to ensure public safety and health.
Risks of having lead in drinking water
Under the Safe Drinking Water Act, the Environmental Protection Agency (EPA) has set the maximum contaminant level goals (MCLGs)—non-enforceable health goals recommended by the EPA for lead—to zero, stating that there is no safe amount, and the harmful metal can cause adverse health issues in small doses, accumulating in the body over time. Children and pregnant women are especially at risk.
According to the EPA, if lead is present in drinking water (even in small amounts), it can cause the following health effects in children:
- behavior and learning problems
- lower IQ and hyperactivity
- slowed growth
- hearing problems
- anemia
The EPA also warns that, in rare cases, lead can cause seizures, coma, and death.
Current EPA regulations of the sampling process of lead and copper in drinking water are currently enforced under the Lead and Copper Rule (LCR). Established in 1991, this rule requires monitoring at multiple locations in each community to ensure that lead levels remain below 15 parts per billion (ppb). If at least 10% of the samples tested are above these levels, then the water utility must increase monitoring, undertake additional corrosion control efforts, and develop and implement training and public education for customers.
In addition to recently passing a bill requiring lead testing in schools, US lawmakers are pressuring the EPA to reduce the standard for lead testing requirements from 15 ppb to 10. This recommendation is in line with lead contamination guidelines established by the World Health Organization, and the EPA is expected to publish a new version of the LCR in 2017.
With these recent lead testing developments in mind, you might be wondering “How Does Lead Get into Drinking Water? How Can Local Municipalities Remove It?”
How does lead get into drinking water?
Lead is not usually found in drinking water (either in the water source or in the chemicals used to treat the drinking water), but when it is present at the tap, it is typically attributed to the corrosion of lead that was already present in plumbing fixtures and/or fittings in the utility distribution system or plumbing inside homes and buildings.
There is a possibility that if your water is delivered to you from a groundwater source, it may contain pollutants from various environmental contaminations. Although unlikely, the possibility does exist.
Typical lead-contaminated fixtures and fittings
In general, the extent of the corrosion and amount of lead that might contaminate drinking water can be affected by:
- the acidity/alkalinity of the water
- the types and volumes of minerals present in the water
- the temperature of the water
- how much wear the pipes have been exposed to
- how long the water sits in the pipes
- whether or not there are protective scales and/or coatings inside these materials
How can local municipalities remove lead from drinking water?
As with most water treatment challenges, there are often several reliable solutions. When it comes to lead in drinking water, other than suggesting that municipalities consider replacing older piping, systems, and fixtures that contain lead, these are the methods we generally explore:
1. Controlling water chemistry and corrosiveness
Any kind of water chemistry control/manipulation is generally based on the evaluation of several factors, including the:
- state of lead oxidation and partitioning
- impact of pH, alkalinity (dissolved inorganic carbon), and orthophosphate on lead solubility
- impact of dissolved inorganic carbon and orthophosphate on lead solubility at a higher pH
Controlling water chemistry to treat lead contamination and promote corrosion control can be extremely complex, so be sure to consult an experienced water treatment company that can perform a thorough treatability study to address your needs (see more information about treatability studies here). They should have a detailed understanding of the local and federal regulatory requirements your municipality needs to meet.
In general, some solutions to controlling lead via water chemistry (depending on the water makeup and local drinking water regulations) can include:
- pH adjustment chemicals (lime, caustic soda, and/or soda ash)
- aluminum coagulants to control lead solubility
- lime softening to remove hardness and reduce alkalinity
- orthophosphate (a number of possible combinations of pH, redox, dissolved inorganic carbon, and orthophosphate can reduce the lead solubility to < 15 ppb)
2. Technology/treatment solutions for potable water generation
After your water source is sufficiently tested for lead and a treatability study has been completed, conventional potable water treatment processes can be considered. Again, be sure to consult a water treatment company that can work with you to offer the best possible solution for your needs, as there are usually several treatment options available that might work.
These can include:
- pH and redox adjustments
- coagulation
- lime softening/conditioning
- phosphate buffers
- flocculation
- clarification
- filtration
- orthophosphate addition
- final oxidation adjustment (residual disinfection and oxidizing conditions)
Be sure to weigh effective treatment options against potential negative impacts
Efforts to control lead by adjusting pH, redox, alkalinity, and/or adding orthophosphate must be carefully considered to ensure municipalities properly treat water for their communities while avoiding the potential negative impacts. Some of the impacts you should work with your water treatment company to avoid are:
- scaling of pipes and appurtenances
- microbial growth
- failing to meet other regulatory requirements while treating for lead (e.g., disinfection byproducts)
- creating noncompliant discharge with corrosion control chemicals such as zinc and orthophosphate
U.S. drinking water utilities are continually challenged to meet stringent requirements when finding sources, providing treatment, and distributing high-quality water to customers in a cost-effective manner.
SAMCO has over 40 years of experience finding solutions for a wide variety of water treatment challenges, so if you have any questions about whether or not SAMCO might be able to help you, please don’t hesitate to reach out to us at our contact page. You can also visit our municipal water section on our website to learn about some of the potential benefits of working with SAMCO in this industry.