|MadSci Network: Medicine|
The consensus of both the US EPA and the World Health Organization is that pH of itself is not a threat in drinking water below 6.5 or above 8.5. The US Secondary Drinking Water Standards recommend pH 6.5 to 8.5, whereas WHO says 6.5 to 9.5. Secondary Drinking Water Standards are supposed to be about esthetics, and acid water (pH<6.5) may have a metallic taste, whereas alkaline water (pH>8.5) may taste of dissolved minerals and be "hard." Extreme pH (<4, >10) may irritate skin and eyes, but the digestive tract is remarkably tolerant of extreme pH, as some foods may be very acid or alkaline. Extreme pH (especially acidity) may etch the insides of water pipes so that the water contains dissolved substances that are threatening to health. However, the new plastic water pipes that are used in most homes are largely unaffected by acid or alkali and unlikely to contribute anything to water that could hurt us.
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Dean O. Cliver
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