Submersible and Sewage Pumps for Septic Tanks

By Steve Crews · Last updated June 22, 2026

Two terms, one overlap

These two labels sound like they should mean the same thing, but they do not.

Submersible is a construction term. A submersible pump is designed to run underwater, sealed so the motor does not flood, and cooled by the liquid surrounding it. It can be a sewage pump, an effluent pump, or even a clean-water sump pump. The word tells you how the pump is built, not what it moves.

Sewage is a content term. A sewage pump handles raw household wastewater that still carries solid material: everything that goes down your drains and toilets before any treatment. Residential sewage pumps are typically rated to pass solids up to about 2 inches without clogging. The word tells you what the pump handles, not how it is built.

Most residential sewage pumps are submersible, so the terms overlap in practice. But in a septic context, calling everything a “sewage pump” causes confusion, because the pump in most septic systems handles effluent, which is liquid that has already settled in the tank and had solids removed.

Does your septic system even have a pump?

Probably not. A conventional gravity-fed septic system has no electrical components at all. Wastewater leaves the house, enters the tank, solids settle to the bottom as sludge and grease floats to the top as scum, and the relatively clear liquid in the middle flows by gravity out to the drain field. No pump, no float switch, no control panel.

Pumps appear when the geometry does not allow gravity to do the work. The U.S. EPA’s SepticSmart program identifies several situations: the drain field is uphill from the tank, the design uses pressure dosing to distribute effluent evenly across the field, or an advanced treatment system (mound, drip-irrigation, sand filter) requires timed doses rather than a continuous trickle. The National Environmental Health Association notes that timed pressure dosing is key to long-term drain field health in soils that would otherwise saturate in one spot.

If you have a control panel on a post near your tank, a small electrical alarm box, or anything a prior owner described as a “pump system,” you have a pump. If you are unsure, your county health department has the original permit on file.

Sewage ejector pumps: the basement case

Sewage ejector pumps (sometimes called sewage lift pumps) solve one specific problem: a bathroom or laundry that sits below the elevation of the main drain line. A basement bathroom 8 feet underground cannot drain uphill by gravity. Instead, the waste falls into a small sealed basin (the ejector pit), and the pump lifts it up to the main horizontal drain that eventually reaches the septic tank.

For a septic homeowner, the ejector pump is part of the upstream plumbing, not the septic system itself. Its discharge feeds the same main drain line as the rest of the house. The pump does add to the total solids load entering the tank, which is worth keeping in mind when setting your pumping schedule.

These pumps typically come as kits: the basin, the lid with fittings, the submersible sewage pump, and a float switch. Equipment costs run roughly $100 to $400. Installed by a licensed plumber, a complete ejector pit setup commonly comes to $800 to $2,000, depending on access, local labor rates, and whether the pit already exists or needs to be cut into a concrete floor.

Grinder pumps are a more powerful variant used where solids must travel through small-diameter pipes or long runs. They have cutting blades that reduce waste to a slurry before pumping. Some community low-pressure sewer systems and shared septic setups use a grinder pump at each property. Equipment alone runs $500 to $1,500, and they need more maintenance than a standard sewage pump because the cutting mechanism wears over time.

If you are replacing an existing sewage ejector pump and the pit and discharge line are already in place, a submersible sewage pump is a manageable DIY job for a handy homeowner who follows local code. Check price on Amazon. Match the pump’s rated horsepower and solids-handling size to what the original installed, and confirm the discharge height matches the pump’s listed head pressure. When in doubt, call a licensed plumber.

Effluent pumps: what most septic owners actually have

If your septic system has a pump chamber (sometimes called a dosing chamber or pump tank), the pump inside is almost certainly an effluent pump. It handles liquid that has already passed through the septic tank and had the bulk of solids settled out. Effluent is not clean, but it is far less solid-laden than raw sewage, which means the pump can be smaller and simpler.

The pump sits inside the chamber on the bottom or on a stand, connected to the discharge pipe and a float switch. When the liquid level rises to the trigger point, the pump sends a measured dose out to the drain field, then shuts off until the next cycle. A high-water alarm float sits above the pump float: if the pump fails and the chamber fills past the alarm point, a light or buzzer alerts the homeowner.

Our guide to septic tank effluent pumps explained covers float switches, timer controls, and alarm systems in more detail. The key point here is that these pumps are a normal, expected part of many septic systems and are not a sign something is wrong. But they do add a component that will eventually need service or replacement.

Effluent pumps for residential pump chambers typically run $150 to $500 for the unit. Labor to access the chamber, pull the old pump, and install a new one adds to that. See the septic tank pump replacement guide for a full breakdown of what that job involves and what to expect from a contractor.

Warning signs and maintenance

Sewage ejector pump: Slow or stopped drainage in the basement bathroom is the most obvious symptom. Other signs include gurgling after you flush, sewage odors near the ejector pit, or the pump running constantly because the float switch is stuck. A pump running nonstop will burn out quickly.

Septic system effluent pump: The high-water alarm going off is the clearest alert. Other signs are effluent odors near the pump chamber, unusually wet or green grass over the pump chamber area (which can mean overflow), or the pump cycling more frequently than normal, which can point to a leaking check valve letting water run back into the chamber between doses.

Both types benefit from an annual check of the float switch and check valve. Most licensed septic professionals inspect the pump and controls when they service the tank. The National Environmental Health Association recommends that systems with mechanical components, including pumps, be inspected at least annually, compared with the three-year minimum for gravity-only systems.

Pump lifespans vary, but 7 to 15 years is a reasonable range for residential effluent and sewage pumps under normal load. Float switch failures are more common than motor failures and are cheaper to fix.

FAQ

What is the difference between a submersible pump and a sewage pump? Submersible describes how the pump is built (runs underwater), while sewage describes what it handles (raw wastewater with solids). Many sewage pumps are submersible, but so are effluent pumps, which handle already-treated liquid in a septic pump chamber. In a septic system, the pump you are most likely to have is a submersible effluent pump, not a sewage pump.

Do all septic systems have a pump? No. Conventional gravity-fed systems have no pump at all. Pumps appear when the drain field is uphill from the tank, when the system uses timed pressure dosing (mound, drip, sand filter), or when a basement bathroom sits below the main drain line. If you are not sure, your county health department can pull the original permit.

Can I replace a sewage ejector pump myself? Yes, in many cases. If the pit and discharge line are already in place and you are just swapping the pump, it is a reasonable DIY job for someone comfortable with basic plumbing and who follows local code. Confirm the replacement pump matches the original in horsepower and head rating. If you are working on a pump chamber that is part of the licensed septic system, hire a licensed professional: confined-space hazards are real, and most states require a licensed contractor for system-side work.

How long does a septic pump last? Residential effluent and sewage ejector pumps typically last 7 to 15 years with normal use. Float switch failures tend to happen before the motor dies and cost less to fix. Annual inspection by a septic professional catches most problems early, before the pump fails completely and backs effluent up into the house.

This article is general educational information and is not professional plumbing, engineering, or legal advice. Always defer to a licensed septic professional and your local health department for the actual work and for rules specific to your area.