304 Stainless Steel has good general corrosion resistance to a range of organic and in-organic fluids. It will have poor resistance to sulfuric and hydrochloric acids. Crevice corrosion may also occur when chlorides (salts) are present in the fluid. Since chlorides are in all natural sources of water it is best to use distilled water whenever possible. Typically, a unit will last about 10-15 years with regular tap water depending on salt content. With water containing chlorides or salt water, the life expectancy of the heat exchanger is reduced to about 3-5 years of continuous use, depending on the quality of the water. It is best to clean the units by back flushing with fresh water if highly contaminated fluids are used.