A sewage ejector pump, also called a pump up ejector system, is used when a bathroom, laundry room or any other type of plumbing fixture is located below the grade of the main sewer or septic line. Because the flow of drain-wastewater depends on gravity, plumbing systems in which these fixtures are located below the level of the main sewer line all require some means of elevating the waste water so it can flow properly.
Most commonly, ejector pumps are used in homes with basement bathrooms or laundry rooms. Not all basements require them, but when the municipal sewer lines come into the house at a higher level, the ejector pump can pump both liquids and solids up into the main sewer or septic line.
Sewage ejector pumps are meant to sit in a sump basin that is cut and dug into the ground below grade. This sump basin collects and holds about 30 gallons of waste, on average, for a moderate-sized home. The drain lines from the various fixtures in the basement area are sloped down into the side of the sump basin, and when the level of wastewater in the sump basin reaches a certain height, a float on the sewage ejector pump is tripped to start the pump. The wastewater is then pumped out of the basin and up to ground level and then out to the sewer or septic tank. Once the level in the basin goes down, the float on the pump turns off until the next time it needs to pump.
The principle is similar to how a groundwater sump pump operates, but instead of rainwater seepage being pumped out of the home, it is waste/sewage being lifted up and out into the main sewer lines or septic field.
A vent is required for a sewage ejector pump installation in order to equalize pressure during pumping and to provide an outlet for sewer gasses. The vent comes out of the sump pump and is either connected to an existing vent (soil) stack or runs up and through the roof.
The common outlet size after the sewage ejector pump is 2”. After the pump outlet line, there is always a check valve to make sure that nothing drains back into the sump basin after the wastewater is pumped out. When it is installed properly, the top of the sump basin is sealed so that no waste or smell can come out of the top of the basin.
Before starting a project that requires the installation of a sewage ejector pump, it is a good idea to check with your local building department. Different areas have different plumbing and building codes and different permit requirements. Any work involving septic or sewer lines is likely to require a permit, and with good reason, since an improper installation would result in quite a mess. To be safe, find out what is required to install a sewage ejector pump legally before you begin. It also wouldn’t hurt to get an estimate from a licensed plumber before deciding to do this project yourself, as this is a fairly advanced project for a DIYer.
Another thing to consider carefully is the size of the ejector pump that you will need. Pumps come in various sizes (horsepower) and the basins are available in different hold capacities. For the average residential installation, a standard pump kit with a 1/2 to 3/4 horsepower motor and 30- or 40-gallon is usually enough, but you can compare prices, specifications, and features to make sure you pick the system appropriate for your project.
Prices for the kits typically run from about $400 to nearly $1,000. This is not an installation you want to repair, though, so make sure you buy quality equipment large enough for your home. Sewage ejector pumps are available at local home improvement stores, online and through your local plumbing supply house. They are also available for commercial applications, but these require a much larger sump basin.