The primary difference between brackish water and seawater is in the amount of dissolved salts/solids. Seawater contains higher amounts of dissolved salts/solids (from 15,000 milligrams per liter (mg/l) to over 40,000 mg/l of total dissolved solids). Water that has only 1,000 – 15,000 mg/l dissolved salts/solids is considered to be Brackish. The greater the salt content of the water, the higher the pressure or electric power needed to treat water using membranes, resulting in higher energy costs.