130Inorganic Chemical Monitoring
All systems must monitor for inorganics. The monitoring for these contaminants is also complex
with reductions, waivers and detections affecting the sampling frequency. Please refer to the
monitoring schedules provided by your state health or drinking water sections for assistance in
determining individual requirements. All transient non-community water systems are required to
complete a one-time inorganic chemical analysis. The sample is to be collected at entry points
(POE) to the distribution system representative of each source after any application of treatment.
Nitrates
Nitrate is an inorganic chemical that occurs naturally in some groundwater but most often is
introduced into ground and surface waters by man. The most common sources are from fertilizers
and treated sewage or septic systems. At high levels (over 10 mg/l) it can cause the “blue baby”
syndrome in young infants, which can lead to serious illness and even death. It is regarded as an
“acute health risk” because it can quickly cause illness.
Every water system must test for Nitrate at least yearly. Systems that use ground water only must
test yearly. Systems that use surface water and those that mix surface and ground water must test
every quarter. A surface water system may go to yearly testing if community and nontransient
noncommunity water must do quarterly monitoring whenever they exceed 5 mg/l in a test. After 4
quarters of testing and the results show that the nitrate level is not going up, they may go back to
yearly testing.
Radiological Contaminants
All community water systems shall monitor for gross alpha activity every four years for each source.
Depending on your state rules, compliance will be based on the annual composite of 4 consecutive
quarters or the average of the analyses of 4 quarterly samples. If the average annual concentration
is less than one half the MCL, an analysis of a single sample may be substituted for the quarterly
sampling procedure.
Total Trihalomethanes (TTHM)
All community water systems serving a population of 10,000 or more and which add a disinfectant
in any part of the drinking water treatment process shall monitor for total trihalomethanes (TTHM).
The MCL is 0.1 mg/l and consists of a calculation of the running average of quarterly analyses of
the sum of the concentrations of bromodichloromethane, di-bromochloromethane, bromoform and
chloroform.
Lead and Copper Rule
The Lead and Copper Rule was promulgated by the U.S. EPA on June 7, 1991, with monitoring to
begin in January 1992 for larger water systems. This rule applies to all community and nontransient,
noncommunity water systems and establishes action levels for these two contaminants at the
consumer’s tap. Action levels of 0.015 mg/l for lead and 1.3 mg/l for copper have been established.
This rule establishes maximum contaminant level goals (MCLGs) for lead and copper, treatment
technique requirements for optimal corrosion control, source water treatment, public education and
lead service line replacement. Whenever an action level is exceeded, the corrosion control
treatment requirement is triggered. This is determined by the concentration measured in the 90th
percentile highest sample from the samples collected at consumers’ taps.
Sample results are assembled in ascending order (lowest to highest) with the result at the 90th
percentile being the action level for the system. For example, if a water system collected 20
samples, the result of the 18th highest sample would be the action level for the system.