Lead and Copper Rule
Lead and copper are inorganic contaminants that are occasionally found in water supplies and are frequently leached out of plumbing in water systems that have corrosive water. Lead can cause central and peripheral nervous system damage, kidney effects and can be highly toxic to infants and in the developing fetus of pregnant women. Copper causes taste problems and stains porcelain and can also cause stomach and intestinal distress.
Does the lead and copper rule apply to my water system?
Yes, all community and non-transient non-community public water supplies are required to test for lead and copper according to the following schedule.
Sampling Requirements
Samples must always be taken at the designated and approved sites. The chosen sampling sites for lead and copper differ from the sites chosen for bacteriological sampling. Sampling sites for lead and copper are chosen by the age of the houses and the type of plumbing connected to the system. The sites chosen are often sites with the highest risk of lead and copper contamination. A site may have higher risk of contamination if there are lead service lines, copper plumbing, or lead solder. A list of the sites for each system is available from the Drinking Water Program should there be any question.
Samples are “first-draw” tap water samples taken in one liter bottles. These samples must be taken to a state approved lab. Samples must be collected from the kitchen or bathroom cold water tap. Lead and copper samples have a 14 day time frame between the time the samples are drawn and when they need to be preserved at the lab. Generally, homeowners may take the samples themselves rather than the operator.
Frequency of Sampling
Initially, samples must be taken for 2 consecutive six-month periods for one year. The six-month periods are from January 1 to June 30 and July 1 to Dec 31. If the 90th percentile levels of the both sets of samples are ½ the action level or below, the monitoring may be reduced to samples every 3 years. If the 90th percentile levels of the past samples are below the action level but above ½ of the action level, the sampling frequency may be reduced to annual.
If the 90th percentile does not exceed the action level for two consecutive annual monitoring periods, sampling frequency may be reduced to once every three years.
How to compute the 90th percentile
- List the results from the lead and copper samples taken during a six-month period, numbering them in ascending order from lowest, being 1, to highest. The number assigned to the sample with the highest concentration must be equal to the total number of samples taken.
- Multiply the total number of samples taken by 0.9 For example, if there are 20 samples, 20 x 0.9 = 18
- The number that results from step 2 is the concentration in the 90th percentile used for comparison to the action level.
- For water systems serving fewer than 100 people that collect only five water samples, the 90th percentile is measured by the average of the highest and the second highest concentrations.
Note: this computation can also be easily done by a representative in the Drinking Water Program and is in no way required to be complete upon submission of results.
System(population) |
Number of sampling sites (initial monitoring) |
Number of sampling sites (reduced monitoring) |
>100,000 |
100 |
50 |
10,001 to 100,000 |
60 |
30 |
3,301 to 10,000 |
40 |
20 |
501 to 3,300 |
20 |
10 |
101 to 500 |
10 |
5 |
<=100 |
5 |
5 |
Action Levels, Health Effects and Sources
The Lead Action Level is 0.015 mg/L. Adverse health effects of elevated lead levels for children include: altered physical and mental development; interference with growth; deficits in IQ, attention span and hearing; and interference with blood synthesis. In adults, the adverse health effects of elevated lead levels can increase blood pressure and shorten the gestational period.
The Copper Action Level is 1.3 mg/L. Adverse health effects of elevated copper levels include: Stomach and intestinal distress and Wilson’s disease.
Elevated lead and copper levels in drinking water are usually caused by corrosion of interior household pipes and fixtures (i.e. lead solder, lead or copper pipes and brass faucets).
If your test results are higher than the action levels listed above your water system must:
- Notify the Drinking Water Program and complete the public notices as required.
- Work with the state agency to determining the best way to reduce the level of contaminate in your water supply.
- Begin water quality parameter monitoring.
- Explore treatments to reduce corrosion rates.
- Complete public education, as required.
Additional information
More information on Lead contamination can be found in SD state pamphlet “Lead and your Drinking Water” and EPA's WEB page addressing the Lead & Copper Rule.
