Absolutely pure water has a pH value of 7.0. In Colorado, the pH of well water normally is between 6.5 and 8.5. Water with pH lower than 5 may cause problems due to corrosion because many metals become more soluble in low-pH waters. A pH value higher than 8.5 indicates that a significant amount of sodium bicarbonate may be present in the water. Calcium and magnesium cause water hardness and result from limestone-type materials in underground soil layers.
Separate values are of minor concern but they are combined for calculating hardness.
Hard water also causes greasy rings on bathtubs, film on dishes or hair after washing, and poor laundry results. Problems caused by hard water in bathing or washing can be overcome by the use of synthetic detergents or packaged softening compounds. The hardness of water may be removed by a water softening unit containing exchange resins. Do not use softened water for Gardens, lawns or plants. A commonly used classification for hardness is given in Table 3.