A Goulds septic tank pump is a key component of a septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations. Other components, typically required by local governments are check valves, ball valves and high alarms. In the USA approximately 25% of the population relies on septic tanks. In Europe, they are in general limited to rural areas only. Since a septic system requires a drainfield that uses a lot of land area, they are not suitable for densely built cities. Periodic maintenance is required to remove solids that settle and eventually fill the tank.