132Number of Water Quality Parameters per Population
System size # of sites for water (no. of persons served) quality parameters
100,000 25
10,001-100,000 10
3,301 to 10,000 3
501 to 3,300 2
101 to 500 1
<100 1
Water systems which maintain water quality parameters reflecting optimal corrosion control for two
consecutive six-month monitoring periods qualify for reduced monitoring. After three consecutive
years, the monitoring frequency can drop to once per year.
All large water systems must demonstrate that their water is minimally corrosive or install corrosion
control treatment regardless of lead and copper sampling results.