How do sewage ejector pumps work
Sewage ejector pumps are used in conjunction with a sump basin. The sump basin is usually dug or cut into the ground below grade. The sewage ejector pump itself sits inside the sump basin. The sump basin is plumbed to collect all of the wastewater from the affected fixtures (usually all of the basement fixtures). To get the wastewater to the basin, the plumbing lines are sloped at the appropriate grade so that they flow with gravity into the basin.
When building a moderate size home you can expect to install a sump basin that collects and holds approximately 30 gallons of waste. This is an average and the total capacity needed or handled will vary depending on the unit and other factors.
Once the wastewater reaches a specific height in the basin the sewage ejector pump goes to work when the pump is tripped by a float rigged to tell the pump to start. The pump itself is fitted with spinning impellers to aid with the intake of the raw sewage through the bottom of the pump.
From there the impellers force the raw sewage under pressure out of the outlet and then into the discharge pipe. From there the wastewater travels in the sewage lines to the main city line or to the septic tank depending on your available utilities. When the wastewater level in the basin goes down, the float hooked up to pump turns off until the next time the level hits the trip line and it needs to pump again.
Standard sewage ejector pumps are generally designed to handle up to 2”diameter solids. It’s important to note that these pumps do not have grinding blades and are considered to be able to handle high volume/ low-pressure submersible solids.
Things to consider
System Requirements
A vent is always required for a sewage ejector pump installation in order to equalize pressure during active pumping and to provide an outlet for sewer gasses during pumping and while the sewage is being held in the basin. The vent usually comes out of the sump pump and is connected either to an existing vent (soil) stack or runs up and then through the roof.
The most common outlet size after the sewage ejector pump is 2”. After the pump outlet line, there is usually a check valve to ensure that nothing drains back into the basin after all the wastewater is pumped out of the basin. When installed properly, the top of the sump basin is securely sealed so that waste fumes are not leaking from the basin into the air.
Planning Considerations
Before starting a project that requires the installation of a sewage ejector pump, you will want to consult with your local building department. Different areas will have different plumbing and building ordinances, codes, and permit requirements. Any work involving septic or sewer lines is will most likely require a permit and an inspector.
To be safe, you are encouraged to find out what is required to install a sewage ejector pump legally before you begin. In many cases, you will need a licensed plumber or company to complete the work.
