Hard and Soft Water

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What is hard water and what can I do about it?

Hard water is simply water that contains two harmless minerals - calcium and magnesium. These minerals make the water hard to develop a sudsy lather. Water is considered "hard" if it measures more than 120 parts per million or 7.0 grains per gallon. Although hardness does not affect the safety of the water, some customers may find it to be inconvenient. Hardness minerals may also contribute to scaling in teapots, spots on dishes and residues on plumbing fixtures and glass shower doors.

The table below lists the range of hardness, sodium, and pH for each source water type supplied by SJWC. View our Water Supply Map to determine what predominant source type serves you.

  Groundwater Imported Surface Water Mountain Surface Water
Hardness as CaCO3 (mg/l) (ppm) 183 - 440 77 - 153 84 - 198
Hardness grains per gallon 11 - 26 grains 4 - 9 grains 5 - 12 grains
pH 7.25 - 8.0 7.0 - 8.7 7.4 - 7.7
Sodium (mg/l) 17 - 42 24 - 73 13 - 20


My showerhead and shower doors have a white film on them. What causes it and what should I do about it?

The white film is the residue of hardness and other minerals in the water. When the water is heated or evaporates, the minerals leave a white coating on items such as showerheads, shower doors, glasses, coffee pots, etc.

Although harmless, most people don't appreciate a white film on these household items. A soaking in vinegar can help dissolve the spots. Make sure you rinse the items carefully after the vinegar "bath" before using them. This method is less practical for shower doors. Some commercially available products may help. In the case of shower doors, prevention is the best medicine. Wipe down the doors with a sponge or towel after every shower.