MAW softens our treated water to around 140 mg/L, which is considered moderate for this area of the country. Softening to this level produces high-quality drinking water and prevents corrosion, which is important for maintaining water quality and protecting public health (leaching of lead and copper, etc.). The level of total dissolved solids (TDS) will also be much lower with Missouri American Water. On average, Eureka’s wells have about 800 mg/L for TDS. In comparison, the U.S. Environmental Protection Agency (EPA) non-enforceable secondary standard for TDS is 500 mg/L, and Missouri American Water averages 170–300 mg/L for TDS in St. Louis County.