The "Precipitation Test" or ("Visual Microscope Test") is a visual test for water hardness. It utilizes hardness chemicals that draw sediment, particulate matter, and solid impurities out of solution into suspension so they become visible. This test reveals 'turbidity', which is the cloudiness or haziness of water due to small particulate matter. These impurities are in your water, but you usually don't see them because particles smaller than 20 microns are invisible to the naked eye. The difference in purity and clarity of our filtered, soft water can be seen in the comparison house water samples below.