Malfunctioning or improperly constructed and maintained private sewage disposal systems can pose serious health hazards. The Illinois Department of Public Health (IDPH) regulates the installation of all private sewage disposal systems that have no surface discharge (such as septic tanks and seepage fields) as well as those that discharge treated effluent up to 1,500 gallons per day to the ground surface (such as sand filters and aerobic treatment systems). Staff also review and approve plans for private sewage disposal systems and alternative private sewage disposal systems before construction. There are about 90 local health agencies in Illinois that also review sewage disposal system construction plans, either by authority of a local ordinance or as an "agent" of the Department. IDPH also licenses or certifies Private Sewage Disposal Installation Contractors, Private Sewage Disposal Pumping Contractors, Portable Sanitation Businesses, Portable Sanitation Technicians and Portable Sanitation Technician Trainees.