Solids that dissolve in water are called total solids; this class includes whole solids as well as suspended particles. Total solids exist primarily in the form of chemicals and minerals, such as calcium, chlorides, phosphorous, iron, nitrate, sulfur and other ionic particles that pass through porous filters. These substances primarily occur in solid form, while suspended particles and particulate solids include silt, sand and clay particles, plankton, algae and other organic debris.
Some total solids, such as naturally occurring minerals, rocks and organic earthen debris, do not pose risks to the surrounding water, or change its physical and chemical properties. However, some total solids, particularly those derived from chemicals and synthetic substances, may introduce harmful toxins into rivers, lakes, streams and other bodies of water. Total solids may accrue in an area over a period of time, or infiltrate a location en mass when deposited in large quantities through spills or improper disposal. High concentrations may carry large quantities of toxins, which then cling to suspended particles and disrupt critical ecosystem functions, such as the ability of plants and vegetation to absorb water. High concentrations of total solids may impair drinking water taste and quality, reduce the efficiency of wastewater treatment plants and alter water clarity.