Drinking Water Regulations - The Drinking Water - page 39

• Use of lead materials —The use of solder or flux containing more than
0.2% lead or pipes and pipe fittings containing more than 8% lead
is prohibited in public water supply systems. Public notification is
required where lead is used in construction materials of the public
water supply system or where water is sufficiently corrosive to cause
leaching of lead from the distribution system or lines.
• Wellhead protection —All states are required to develop wellhead pro-
tection programs designed to protect public water supplies from
sources of contamination.
The USEPA developed the National Drinking Water Regulations to meet the
requirements of the SDWA. These regulations are subdivided into National
Primary Drinking Water Regulations (40 CFR 141), which specify maximum
contaminant levels (MCLs) based on health-related criteria, and the National
Secondary Drinking Water Regulations (40 CFR 143), which are unenforce-
able guidelines based on aesthetic qualities, such as taste, odor, and color of
drinking water, as well as on nonaesthetic qualities, such as corrosivity and
hardness. In setting MCLs, the USEPA is required to balance the public health
benefits of the standard against what is technologically and economically
feasible. In this way, MCLs are different from other set standards, such as
National Ambient Air Quality Standards (NAAQS), which must be set at lev-
els that protect public health regardless of cost or feasibility (Masters, 1991).
Note: If monitoring the contaminant level in drinking water is not eco-
nomically or technically feasible, the USEPA must specify a treatment
technique that will effectively remove the contaminant from the water
supply or reduce its concentration. The MCLs currently cover a number
of volatile organic chemicals, organic chemicals, inorganic chemicals,
and radionuclides, as well as microorganisms and turbidity (cloudiness
or muddiness). The MCLs are based on an assumed human consumption
of 2 liters (roughly 2 quarts) of water per day.
The USEPA also creates unenforceable maximum contaminant level goals
(MCLGs), which are set at levels that present no known or anticipated health
effects and include a margin of safety, regardless of technological feasibility
or cost. The USEPA is also required (under SDWA) to periodically review the
actual MCLs to determine whether they can be brought closer to the desired
MCLGs.
Note: For noncarcinogens, MCLGs are arrived at in a three-step process.
The first step is calculating the reference dose (RfD) for each specific con-
taminant. The RfD is an estimate of the amount of a chemical that a person
can be exposed to on a daily basis that is not anticipated to cause adverse
systemic health effects over the person's lifetime. A different assessment