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Water Hardness

Water hardness is due to concentrations of calcium and magnesium in water and is expressed as milligrams per liter (mg/L) of calcium carbonate. Calcium and magnesium are naturally occurring elements found throughout watersheds and are also found in surface and groundwater sources. “Ideal” water hardness for drinking water ranges between approximately 50 to 100 mg/L. Above this level, hardness can contribute to scaling of water heaters and boilers. Water with hardness below this level tends to be more aggressive and can cause deterioration of the inner surface of pipes, eventually leading to pinholes or leaks.

Hardness in the District’s treated drinking water ranges between 160 and 350 mg/L with an average of about 250 mg/L. 

Hardness in the Authority’s treated drinking water ranges between 50 and 380 mg/L with an average of about 120 mg/L.

Our drinking water sources are seasonal and, as a result, hardness levels can vary over the course of the year. When groundwater is the main drinking water source, the tendency is to find higher hardness levels due to high contact with underground mineral deposits. When surface water is the source, hardness levels can vary due to the dilution of river water by snowmelt and rainfall as well as less contact with soil minerals. Generally speaking, surface water is softer than groundwater. 

A water hardness test kit can be purchased at most local home improvement centers and can be used to set the water softening system to the appropriate level (50-100 mg/L). This will give the benefits of softer water, and help the homeowner avoid problems associated with completely softened or zero hardness water.  

Water Softeners

Water softeners are used to treat excessive hardness of tap water. Most people choose to install softeners because they prefer the benefits of “soft” water: soap tends to lather more easily, there are fewer spots on dishes, and less detergent is needed for washing. Many of the water softeners installed today are flow-through systems, which remove all hardness. Water that lacks any hardness is considered aggressive and can cause pipe problems over time due to corrosion. One way to avoid this problem is to install a small line with ball valves in the plumbing that allows some water to bypass the softening system. 

A common term used in the water softener industry is grains per gallon. Grains per gallon refers to the amount of softening salt grains needed to treat a gallon of water. There is a direct correlation between total hardness and grains per gallon. Simply dividing the total hardness by 17.1 gives the grains per gallon equivalent.