Non-community public water systems are those that serve a non-residential population of 25 or more people at least 60 days a year. The approximately 5,000 non-community water systems in Illinois must meet water quality standards established by the United States Environmental Protection Agency. It is the division's responsibility to review construction plans and to routinely inspect and sample these supplies. About 85 local health departments assist in conducting this program, either by authority of a local ordinance or as an "agent" of the Department. The division also investigates complaints about semi-private water systems.