Lead & Copper

Lead & Copper Rule
Water utilities in the U.S.A. are required to comply with the Environmental Protection Agency's (EPA) Lead and Copper Rule. This rule was passed in 1991 and sets the action level for lead in drinking water at 15 parts per billion (ppb). This means that utilities must ensure that water from the customer's tap does not exceed this level in at least 90% of the homes sampled.

Action Level: Exceeds Action Level if more than 10% of the homes tested have lead levels greater than 15 parts per billion
Maximum Contaminant Level Goal: Zero parts per billion
Source of contaminant: corrosion of plumbing systems

Action Level: Exceeds Action Level if more than 10% of the homes tested have copper levels greater than 1.3 parts per million
Maximum Contaminant Level Goal: 1.3 parts per million. Treatment techniques required.
Source of contaminant: corrosion of plumbing systems

On June 1, 2001, the Maui Department of Water Supply (DWS) began a corrosion control program by adding phosphates to the Upcountry water supply. The Hawaii State Department of Health, Safe Drinking Water Branch mandated the use of phosphates to reduce the levels of lead that have been found in some homeowners' drinking water. Phosphates create a protective film on the inside of the pipe, slowing the electrochemical processes that lead to corrosion. On June 28, 2004, the DWS stopped the use of phosphates in the Upcountry water system.

Soda Ash
To replace the phosphate, the DWS implemented a high pH, low alkalinity treatment, using soda ash. The DWS is required by the State to implement and maintain an approved corrosion control program in order to minimize lead leaching. The pH of the water is approximately 8.8, not to exceed 9.4. The higher pH should make the water less corrosive.

Soda Ash is the common name for sodium carbonate (Na2Co3). It is a sodium salt and is alkaline. It is commonly used in water treatment for pH adjustments and for corrosion and scale control. It is National Sanitation Foundation / American National Standards Institute (NSF / ANSI) Standard 60 certified safe drinking water treatment.

Soda Ash works by producing an increase in the final sodium content, pH and alkalinity. The combination of higher pH and alkalinity can dramatically reduce lead solubility relative to lower pH and lower alkalinity water. The strategy is supported by scientific theory, laboratory data, and the practical experiences of hundreds of U.S. utilities.