Pump Systems



The septic system comprises several integral components. Let’s begin with the pump chamber, typically utilizing a 1,200-gallon septic tank, though the size may vary based on requirements. Effluent from the septic tank flows into the pump chamber, which is located out of sight to the left. The septic tank plays a crucial role in liquefying wastewater and retaining solids. It’s essential to prevent large solids from reaching the drain field as they can damage the soil’s absorptive interface.

At the bottom of the tank, you’ll find the pump, represented by a blue box-like object. Pump sizes vary depending on the distance of pumping, the vertical lift required, and the purpose of pumping. Some systems only need to overcome elevation differences, while others utilize the pump to evenly distribute effluent, requiring additional power to pressurize the piping. In residential systems, pumps generally range from 1/4 to 1/2 horsepower. Adjacent to the pump, you’ll notice three float switches. The lowest float serves as the “pump enable/off” float. When in the “up” or “on” position, it activates the pump, allowing it to run. The pump can continue running even after the middle “pump on” float tips up. Once the pump “on” float returns to its original position, the pump will continue operating until the lower float turns it off. During normal operation, the pump chamber fills with effluent from the septic tank, and the float switches ensure the effluent remains between the two lower floats.

Typically, these floats are adjusted to discharge a volume of effluent between the daily flow from the house and one-quarter of the daily flow. For a four-bedroom house, this equates to a range of 150 to 600 gallons of effluent per dose. The distance between the floats determines this volume. As most 1,200-gallon septic tanks have a liquid depth of 48 inches, each inch of depth corresponds to approximately 22 gallons. Therefore, the floats should be set between 7 and 22 inches apart.


In practice, the floats are generally set closer to 7 inches to maintain constant submersion of the pump. This is crucial as sewage and sewer gases are corrosive, and submerging the pump in effluent helps mitigate the corrosion process. Although a larger tank would allow for greater pumping volume, it incurs higher costs without providing any advantages beyond increased expense.

The top float serves as a high-water alarm. If, for any reason, the pump fails to start when the “pump on” float tips up, the high-water alarm will audibly and visually alert the user of a problem.