In modern fountains a water filter, typically a media filter, removes particles from the water—this filter requires its own pump to force water through it and plumbing to remove the water from the pool to the filter and then back to the pool. The water may need chlorination or anti-algal treatment, or may use biological methods to filter and clean water.
The pumps, filter, electrical switch box and plumbing controls are often housed in a "plant room". Low-voltage lighting, typically 12 volt direct current, is used to minimise electrical hazards.
Lighting is often submerged and must be suitably designed. High wattage lighting (incandescent and halogen) either as submerged lighting or accent lighting on waterwall fountains have been implicated in every documented Legionnaires' disease outbreak associated with fountains. This is detailed in the "Guidelines for Control of Legionella in Ornamental Features".
Floating fountains are also popular for ponds and lakes; they consist of a float pump nozzle and water chamber.