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. Look online for cheap test strips, or a more accurate water hardness test kit. Most test kits in the United States measure the hardness in "grains per gallon." Multiply this result by the gallons of water your household uses each day, on average (according to your water bill). This is the number of "grains" of hardness the device would soften each day. Choose a softener labeled for about 10 times this number of grains. This means the softener will work for about ten days before it needs some downtime. The average US resident uses 100 gallons of water a day (or 70 gallons if you're only softening indoor water use). For example, your household water hardness has 9 grains per gallon. You use 300 gallons per day, so 9 x 300 = 2,700 grains per day. A softener in the 27,000 grain range (2,700 x 10) is about the right size. Ion exchange softeners are by far the most effective home softener. Most other devices are much less effective, or even just scams. Ion exchange softeners come in two types: Sodium chloride: the most common and most effective type. This adds a tiny amount of salt (sodium) to your water. Potassium chloride: less effective, but useful if you can't have sodium. The potassium can harm people with damaged kidneys or on certain medications that prevent potassium absorption. If you don't want sodium or potassium, pick either type and install a reverse osmosis (RO) filter as well to remove them after softening. Once you've narrowed down the choice to some good models, look at the details. Many softeners refill themselves automatically, going offline for a while during this time. Some do this whenever the softening resin drops too low. Others can be set for a specific time once a week, so you're never caught with hard water unexpectedly. You can buy the softener in one go or lease it for a monthly payment. Besides reducing the upfront cost, leasing it usually comes with a professional installation, so you don't have to do it yourself. Try to get at least two quotes on the installation and lease. . If you decide to install the softener yourself, follow the instructions in the linked article. Most softeners also come with detailed installation instructions, although basic plumbing experience will help.

Summary:
Measure your water hardness Find the right size softener. Choose a type of softener. Find out how to maintain the softener. Check the leasing plan. Install the softener