131The rule also includes the best available technology (BAT) for complying with the treatment
technique requirements, mandatory health effects language for public notification of violations and
analytical methods and laboratory performance requirements.
Initial monitoring began in January 1992 for systems with a population of 50,000 or more, in July
1992 for medium-sized systems (3,300 to 50,000 population) and in July 1993 for small-sized
systems (less than 3,300 population),
One-liter tap water samples are to be collected at high-risk locations by either water system
personnel or residents. Generally, high-risk locations are homes with lead-based solder installed
after 1982 or with lead pipes or service lines. If not enough of these locations exist in the water
system, the rule provides specific guidelines for selecting other sample sites.
The water must be allowed to stand motionless in the plumbing pipes for at least six (6) hours and
collected from a cold water tap in the kitchen or bathroom. It is a first draw sample, which means
the line is not to be flushed prior to sample collection.
The number of sampling sites is determined by the population of the system and sample collection
consists of two, six-month monitoring periods; check with your state rule or drinking water section
for more information.
Sampling Sites by Population
System size - No. of sites - No. of sites
(no. of persons served) (standard monitoring) (reduced monitoring)
100,000 100 50
10,001-100,000 60 30
3,301 to 10,000 40 20
501 to 3,300 20 10
101 to 500 10 5
< 100 5 5
If a system meets the lead and copper action levels or maintains optimal corrosion control treatment
for two consecutive six-month monitoring periods, then reduced monitoring is allowed and sampling
frequency drops to once per year.
After three consecutive years of reduced monitoring, sample frequency drops to once every three
years. In addition to lead and copper testing, all large water systems and those medium- and small-
sized systems that exceed the lead or copper action levels will be required to monitor for the
following water quality parameters: pH, alkalinity, calcium, conductivity, orthophosphate, silica and
water temperature.
These parameters are used to identify optimal corrosion control treatment and determine
compliance with the rule once treatment is installed. The sampling locations for monitoring water
quality parameters are at entry points and representative taps throughout the distribution system.
Coliform sampling sites can be used for distribution system sampling. The number of sites required
for monitoring water quality during each six-month period is shown below.