The white stuff could be hardness scale, or TDS, chlorides or sulfates etc..
You can go to the water company's web site and find their water quality report and then find hardness or total hardness as CaCo3.
Usually they state it as low, average and high, you need the high figure. Or buy a test kit and test it yourself. There is no sense in paying a certified lab what they want for hardness test on city water.
If you have more than 3-4 gpg of hardness, I suggest a correctly sized softener based on the family size, number of bathrooms and the type of fixtures in them and it should have a Clack WS-1 control valve on it. The Clack WS-1 is the latest version of the Fleck piston seal and spacer design and is the easiest and fastest to program and repair and there are no special tools needed as there is with Fleck valves. It was invented by 3 ex Fleck engineers that had a combined 72 years at Fleck. It is a much better valve than the Fleck 5600 or 2510 or 7000. I have sold them all, 18 yrs as a Fleck guy and over 5 yrs selling the Clack WS-1. Out of 2000 Clack WS-1 valves, I've had only 22 problems. When I sold Fleck I had many more problems with fewer valves; because of problems and excessive water use, I quit selling the 7000 just 15 months after it came on the market Feb 1 2005. It is the only Fleck valve that can be compared to the features of the Clack WS-1.
