Secondary Standards for Drinking Water
| Contaminant | Secondary Standard | Adverse Effect |
|---|---|---|
| Aluminum | 0.05 to 0.2 mg/l | Causes color problems. |
| Chloride | 250 mg/L | Causes taste. Adds to total dissolved solids and scale. Indicates contamination. |
| Color | 15 cu | Indicates dissolved organics may be present, which may form THM's; unappealing appearance. |
| Copper | 1 mg/L | Undesirable metallic taste. |
| Corrosivity | Noncorrosive | Causes tastes, odors, deterioration of water system. |
| Fluoride | 2 mg/L | Dental fluorosis (mottling or discoloration of teeth). |
| Foaming Agents | 0.5 mg/L | Unappealing appearance. Indicative of possible contamination. |
| Iron | 0.3 mg/L | Discoloration of laundry (brown, red). Imparts taste. Red stains on plumbing fixtures. |
| Manganese | 0.05 mg/L | Discolors laundry. Imparts tastes. Black stains on plumbing fixtures. |
| Odor | 3 threshold odor number | Unappealing to drink. |
| pH | 6.5 - 8.5 | <6.5 is corrosive; >8.5 is scale-forming and bitter tasting |
| Silver |
0.10 mg/l | Skin discoloration. |
| Sulfate | 250 mg/L | Laxative effect. |
| Total Dissolved Solids | 500 mg/L | Associated with taste, scale, corrosion, and hardness. |
| Zinc | 5 mg/L | Undesirable taste. Milky appearance. |
National Secondary Drinking Water Regulations are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
Rev. 10/23/00
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