Lesson 2 -
Public Drinking Water Supply Standards Information Sheet
Acknowledgement: Taken from "Living on
the Land 2001"
|
Primary Standards Approved by the EPA |
|
| Contaminant | Maximum Contaminant Level |
| Arsenic (As) | 0.05 ppm1 |
| Barium (Ba) | 2 ppm |
| Fluoride (F) | 4 ppm |
| Mercury (Hg) | 0.002 ppm |
| Nitrate (NO3 as N) | 10 ppm |
| Turbidity | 1 turbidity unit |
| Coliforms, Fecal Coliform, E. coli | Cannot be present |
|
Secondary Standards Approved by the EPA |
|
| Contaminant | Maximum Contaminant Level |
| Chloride (Cl) | 250 ppm |
| Color | 15 color units |
| Copper (Cu) | 1 ppm |
| Fluoride (F) | 2 ppm |
| Iron (Fe) | 0.3 ppm |
| pH | 6.5 – 8.5 |
| Sulfate (SO4) | 250 ppm |
| Total Dissolved Solids (TDS) | 500 ppm |
| Zinc (Zn) | 5 ppm |
| Lead/Copper Action Level | |
| Contaminant | Action Level2 |
| Copper (Cu) | 1.3 ppm |
| Lead | 0.015 ppm |
|
Additional Water Characteristics |
|
| Characteristic | Consideration |
| Alkalinity5 | |
| Boron 4,5 | Too much boron is harmful to plants |
| Bicarbonate (HCO3)5 | |
| Calcium (Ca)3,4,5 | High levels increase pH in water and soils |
| Carbonate (CO3)5 | |
| EC (Electrical Conductivity)5 |
Measures salt concentration of water in umhos/cm 0
– 400
excellent |
| Hardness | 0
– 75 ppm soft 75 – 150 ppm moderately hard 150 – 300 ppm hard Over 300 ppm very hard |
| Magnesium (Mg)3,4,5 | Laxative effect, quickly adjusted to by newcomers |
| Potassium (K)4 | Plant nutrient; adds to TDS. Consult personal physician for health implications |
| Silica5 | |
| Sodium (Na)5 | Consult personal physician for health implications |
ppm (parts per million; your report may instead report as mg/l which is an equivalent unit)
If your first-draw sample exceeds these levels, consider the need to take preventive action
Used to calculate hardness
Required for plant growth. Influence on humans or livestock from concentration in water not available. No known health risk
Laboratory us
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