A white precipitate is left behind when I wash my dishes, car or plant leaves. What type of testing should I have?

Yes. Hardness or other minerals in water can cause these problems. The Water Treatment Package would identify the level of Hardness in your water along with other nuisance problems in water. It is also part of the General Naturally-Occurring Minerals and Toxic Metals Package and the Irrigation Water Package. Look under Packages on this web page. Or the Hardness test could be requested individually.