What is Water Hardness

How "hard" is the water in Cambridge?

Water hardness refers to the naturally occurring mineral content of water, commonly calcium and magnesium carbonate. While these naturally occurring minerals are beneficial to your health they can cause problems when heated. CWD's water is "moderately hard" and does not vary throughout the city. Hardness varies slightly by seasons of the year.  When using dishwashers, you may notice "spotting" on glassware, flatware or white residue in kitchenware and showers. Using a high quality dishwasher detergent with a rinse agent will solve this problem. This residue consists mainly of calcium carbonate, the same ingredient found in anti-acid products and not a health risk. The hardness of the city's tap water is typically around 60 parts per million or 3 to 4 grains per gallon.

What is the white residue I sometimes find on cookware, in the shower and even in ice cubes?

White residue is commonly found in showers and kitchenware as the result of dissolved naturally occurring minerals found in water, such as calcium and magnesium carbonate. Mineral particles can also be visible in ice cubes made with tap water. These minerals are beneficial to human health but can build up on surfaces over time. Commercial products are available to remove white residue caused by minerals in water or simply wipe down with common white vinegar

All of the strainers in my faucets are clogging with white particles. What could this be?

Aerators are strainers that attach to your faucet or shower head and break up the flow of water as it leaves your tap. Aerator screens can collect mineral particles found in water and should be routinely cleaned throughout the year and replaced once a year. Particle build up is often white, off white, light brown, or dark brown.

The most common source of build up in aerators is from the hot water heater. 

Dissolved minerals naturally found in our drinking water and can naturally precipitate out in hot water heaters. Over time, these minerals may accumulate at the bottom of the hot water heater and collect in your aerators.

If you are experiencing a calcium carbonate problem, we recommend flushing the hot water heater routinely. Contact a plumber or download instructions for draining your hot water heater.

For additional information, contact the Cambridge Water Laboratory at 617-349-4780.