What Is a Sewage Ejector Pump and How Does It Work?

If your home depends on a sewer, you may wonder—what is a sewer ejector pump and how does it work? Sewage ejector pumps are submersible workhorses that help move solid and liquid waste from your home to the communal sewer line. Only homes with basement laundry or bathroom facilities need a sewage ejector pump, but in these homes, they are vital. Here’s everything you need to know about sewage ejector pumps.

What Is a Sewage Ejector Pump?

A sewage ejector pump is a submersible centrifugal pump that moves liquid and soft solid waste along the residential pipework into the main community sewer line. In normal setups, wastewater, including sewage, moves via gravity from a property's plumbing to the main septic line outside.

But things get dicey if the sewage pipework is below or not far enough above the main septic line. Gravity will need a helping hand, and that's where a sewage ejector pump comes in. It moves the waste up and along the pipes into the main sewer line.

Types of Sewage Ejector Pumps

Sewage ejector pumps come in a wide variety of styles, with various manufacturers using different materials and designs to construct them. However, they can be broken down into three main categories: submersible, self-priming, and vertical.

Submersible Sewage Ejector Pumps

These are the most common type on the market today, and are, as their name suggests, fully submerged in the sump basin. They come in both single-seal and double-seal designs, with double-seals being a little sturdier for pumps that will be kicked on every day, multiple times per day. Some submersible sewage ejector pumps also come with a grinder mechanism that can work to help break down solid wastes further, sort of like the garbage disposal in a sink. For larger households or ones with more frequent usage, the grinder type may help your septic system work more efficiently.

Self-Priming Sewage Ejector Pumps

These types of pumps are used when headroom in the sump basin is lacking; rather than being submersed in the pit, they sit on top of it and fill themselves with water—also known as self-priming. They can be easier to remove for cleaning and service than submersible pumps, and they work best with shallower pits.

Vertical Sewage Ejector Pumps

The oldest style of ejector pumps, these are largely outdated by submersibles and self-priming pumps these days. However, they’re long-lasting, and if your home is older, you may still have one as part of your septic system. In a vertical sewage ejector pump, the motor itself rests on a plate while the pump shaft and discharge pipe are submerged in the pit. Since parts of the pump are outside of the water, they require regular lubrication of the sleeve bearings along their shafts to continue to work properly, and they’re best for less frequent use.

How Does a Sewage Ejector Pump Work?

For a vital piece of equipment, the sewage ejector pump operates rather simply: 

1. The pump sits in the sump basin with a float attached. When the level of sewage in the basin lifts the float, it engages the pump's motor. 

2. When the motor turns on, it forces the solids and liquids out of the basin, down the sewer pipe, and to the main septic line outside the property. 

3. As the basin empties, the float moves back down. When it reaches its minimum level, it signals to the ejector pump to turn off, and the cycle begins again. 

The setup requires a vent to equalize pressure when the pump is active and then release sewer gases. The vent runs from the sump basin and connects to an existing vent stack or runs up the side of the property and out through the roof.

Do You Need a Sewage Ejector Pump?

If your home has a laundry or a bathroom where the plumbing is below the level of the communal sewer line it joins to, then yes, you absolutely need a sewage ejector pump or, in some cases, a sewage grinder pump. 

It's almost certain you'll need one of these pumps if you have a washing machine or a bathroom in your basement. If not, waste will solidify in the pipe, resulting in a sewage backup and overflow nightmare.

Where Is a Sewage Pump Typically Installed?

To work effectively, the sump basin is usually underground in a basement. The ejector pump will sit in a basin (usually plastic or steel) to keep fluids and odors contained while it moves waste up into the sewer lines.

How to Install a Sewage Ejector Pump

While the exact steps for installing a sewage pump will depend on what kind of pump you’ve got, the process is fairly intensive and probably best suited for professionals and extremely confident DIYers.

In general, here’s how the installation of a sewage pump works.

• The installer will need to access your sewage basin, which may involve pulling up a silicone seal around the bolted-down cover—or even cutting into the vent and discharge pipe.

• Then, the old pump, if there is one, must be removed, which usually involves reaching into wastewater to retrieve it. (Like we said, it’s a job that takes confidence!) In order to do this, the check valve must be disconnected, and many experts recommend replacing it each time a new sewer ejector pump is installed. At this point, wastewater above the valve will drain out.

• While the pit is partially drained, the installer should take a moment to inspect the pit itself as well as the pipes and connections to ensure that everything is intact and in good, working order. Otherwise, the new sewer ejector pump won’t solve any problems.

• At this point, a new check valve can be installed, and the pump and adapter can be attached to the discharge pipe. Always be careful not to over-tighten connections, which can cause the fittings to crack.

• In addition, a weep hole must be drilled to keep an air-lock from occurring in case the pipe runs dry. The bottom discharge pipe may also need to be replaced, which involves measuring, cutting, and fitting new PVC pipe for this purpose.

• Once the sewer ejector pump is completely assembled with the discharge pipe attached, it can be lowered into the basin and attached to the new check valve. Now, it’s ready to put to the test!

What Maintenance Does a Sewage Ejector Pump Need?

Ideally, sewage ejector pumps need no maintenance apart from a yearly service by a qualified plumber. During the service, the technician cleans the pump, oils the motor, and carries out a full inspection of the pump, the float, and the connections. They'll also remove any debris wedged in the sump basin.

But homeowners need to do their part, too. It's vital that you only flush waste and toilet paper in systems with a sewage ejector pump. Other items can clog the pump and force the motor to work extra hard to move them. This will shorten the life of the pump and can cause a clog and sewage overflow in your bathroom.

Pros and Cons of a Sewer Ejector Pump

A sewer ejector pump provides the required flow of sewage into the main septic line, something we can’t do. The pros far outweigh the cons and for many homes, this type of pump is more a requirement than an option.

However, there are some drawbacks. These pumps break, and when they do, they are expensive to fix, and your home may not smell too great in the meantime. In demanding cases, water can even start backing up into your basement. 

How Much Does a Sewage Ejector Pump Cost?

Expect to pay between $300 and $800 for a sewage ejector pump. You'll also need to hire a local sewer service or plumber near you for installation. Plumbers often charge by the hour, and the cost to hire a plumber per hour varies between $45 and $200. The annual service costs around $130, but you may be able to save by getting a complete yearly plumbing inspection for your whole home.

Some areas may also require a permit to install an ejector pump. This is because cities will need to confirm your improvements are in compliance with local drainage points. In general, plumbing permits cost $50 to $500.

Sewage Ejector Pumps vs. Sewage Grinder Pumps

Sewage grinder pumps are more powerful than sewage ejector pumps. These pumps are able to grind up raw sewage before passing them into the sewer line. They're also able to handle tougher solids and at a higher volume.

Note that sewage grinders aren't suitable for use with septic tanks, as they grind the sewage too finely so the liquids and solids never separate, and the liquified solids travel through the secondary system into the leaching field.

If you have a septic tank, then you'll need a sewage ejector pump. You'll also use an ejector pump if you have a vertical lift of less than 70 feet and if you're pumping the sewage less than 750 feet.

Sewage Ejector Pumps vs. Sump Pumps

The main difference between sewage ejector pumps and sump pumps is the contents they pump. Sewage ejector pumps help remove home sewage waste—both solid waste and liquid gray water—via your sewer line. Sump pumps help move excess groundwater outside and prevent flooding after a heavy rainstorm.

Both systems are commonly used in homes built in lower elevations, such as below the water or sewer line.