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2.6 CHAPTER TWO

TABLE 2.1 Presently Enforceable USEPA Primary Drinking Water Standards

Inorganics
A list of some 20 chemical elemental or compound materials. Note that the traditional treatment
would have little or no effect in the reduction of many of the materials in this list.
Synthetic organic contaminants
A list of over 30 materials, for the most part manufactured for use as herbicides and pesticides. Many
of these would require more than the usual filtration treatment to achieve the required reduction.
Volatile organics
A group of over 20 materials, essentially solvents used in manufacturing and other activities for
cleaning.
Maximum contaminant level
Contaminant (except as noted), mg/L
Surface Water Treatment Rule (SWTR)
Turbidity
Not to exceed 5% of monthly samples
0.5 ntu
Microbiological
Total coliform bacteria More than 5% of samples positive
Disinfectant residual/heterotrophic plate count More than 5% sample with less than
detectable residual and HPC 500/mL
Radionuclides
Radium 226 and 228 5 pCi/L
Gross alpha radioactivity 15 pCi/L
Beta and photon radioactivity 4 rem/yr*
Interim Enhanced Surface Water Treatment Rule (IESWTR)--system population 10,000 or more
Turbidity
Not to exceed 5% of monthly samples 0.3 ntu
Disinfectants-Disinfection By-products Rule
Stage 1 :
Disinfection by-products
Bromate 0.010
Chlorite 1.0
Haloacetic acid (five) (HAA5)
0.060*
Total trihalomethanes (TTHM) 0.080t
Total organic carbon removal
Source water TOC, mg/L Percent TOC removals for source water alkalinity, mg/L
0 to 60 > 60 to 120 <120
> 2.0 to 4.0 40.0 30.0 20.0
> 4.0 to 8.0 45.0 35.0 25.0
50.0 40.0 30.0
> 8.0
Alternatives to TOC reduction
Typical example--reduction of TTHM and HAA5$
TTHM 0.0401
HAA5 0.030 t
Note: Values in mg/L unless otherwise noted.
*The contribution of this category of radionuclides is to be computed. Tritium at 20,000 pCi/L and strontium 90
at 8 pCi/L, respectively, are computed to give no more than 4 rem/yr.
tFour quarterly samples; compliance based on running annual average of all sites.
*One of the four alternatives permitted (see Federal Register for others).