Water softeners use salt to remove minerals, or hardness, from water, which protects fixtures and appliances from mineral buildup (scale). But all that salt ends up down the drain and in local freshwater streams, where it can pollute water.
Use a blending valve to get the benefits of softened water while reducing your salt use. With this feature, you can adjust your water hardness so the water is not mineral-free, but low enough in minerals that scale buildup is minor or unnoticeable.
How blending valves save salt
Blending valves, sometimes called mixing valves, divert a small portion of your hard water supply around the water softener and mix it back into water that has been softened. This results in water that is mostly soft, but has a small amount of hardness. Because your water softener doesn’t have to soften as much water, it uses less salt.
The hardness of water is measured in grains per gallon (gpg). If your home’s water supply has a natural hardness of 20 gpg, and a blending valve is set to 2 gpg, the water in your home will contain 10% of its original hardness. That means you will use 10% less salt than you would if your water was fully softened. The higher the hardness level, the less salt you will use. However, more hardness means more potential scale.
Get the softness level you want
Blending valves can be set to different softness levels based on your preferences. Below are the levels of water hardness defined by the U.S. Geological Survey as the concentration of calcium carbonate in grains per gallon (gpg).
0-3.5 gpg
SOFT.
Water that has gone through a water softener has a hardness of 0 gpg. At this level, scale impacts will be minimal, but softening to this level requires the most salt.
3.5-7 gpg
MODERATELY HARD.
The U.S. Dept. of Energy considers this level of
hardness to be ideal. Blending
water to this level would reduce Madison residents’ salt use by about 15-35%.
7-10.5 gpg
HARD.
This level is comparable
to the natural hardness of Lake Michigan (7.5-8
gpg). Many residents of
communities that use Lake Michigan water do not use
water softeners.
10.5+ gpg
VERY HARD.
All water in the
Madison area is very hard,
ranging from 15-32 gpg depending on the well.
.
Keeping water fresh with blending valves
This District has a goal to increase the use of blending valves. We get too much salt, mostly from water softeners, so we’re working to keep water fresh by reducing the amount of salt used by softeners.
Many water softeners have a blending valve or a setting that controls the blending valve on the unit. A service technician can program this setting to your desired softness, helping you balance your soft water use and your salt use.
This article was written by District pollution prevention specialist Emily Jones. For more information on salt reduction strategies in your home, visit our Salt Reduction for Residents page, or learn about Wisconsin Salt Wise strategies.
