How hard is our water?
Our water is on the soft side. Water hardness, a measure of calcium and magnesium concentrations in the water, is the result of a natural accumulation of salts from contact with soil and geological formations. When referring to household use, the term hardness is applied to the soap-neutralizing power of the water and is commonly expressed in grains per gallon (gpg.) Generally, water with less than 4 gpg hardness is soft, water with 4-7 gpg is moderate, and water with greater than 7 gpg is hard.

The water that comes from MMWD's reservoirs ranges in hardness from 3-5 gpg, while the water that is imported from the Russian River ranges in hardness from 5-7 gpg. MMWD blends the Russian River water with reservoir water, so the average hardness of the water served to customers in the northern and central portions of our service area is 4-6 gpg. The water hardness for customers in southern Marin is 3 gpg.

Show All Answers

1. Does our water contain fluoride?
2. How hard is our water?
3. What are disinfection byproducts?
4. Should I be worried about cryptosporidium?
5. Why is my water cloudy sometimes during the winter?
6. What is the blue-green sheen on some of the district’s reservoirs?
7. Can a home water treatment device make my water even cleaner?
8. Is bottled water better than tap water?