Sketch of a common sewage grinder pump used in a modern basement Installation Guide for Septic Pumps

  • SEPTIC PUMP INSTALLATION - CONTENTS: A guide to installing Septic tank pumps, septic grinder pumps, septic effluent pumps. What is the difference between a sewage ejector pump or grinder pump and a sump pump? Why would using a sump pump in a sewage holding tank lead to trouble?
  • POST a QUESTION or READ FAQs about buying sewage pumps, sewage ejectors & grinder pump installation procedures

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Guide to septic pump or sewage ejector pump installation:

This article describes sewage ejector pumps and residential or light commercial-use sewage grinder pumps used to move wastewater from low areas to a septic tank or to a municipal sewer line.

This septic pump or sewage pump article series will help you diagnose and fix problems with sewage pumps, perform normal sewage ejector pump maintenance, and when needed, select and buy a sewage pump.

This article series also explains the differences between and gives installation and maintenance advice for Sump Pumps, Sewage Ejector Pumps, Septic Grinder Pumps, Sewage Pumping Stations, & Septic Pump Alarms. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted.

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Guide to Sewage Grinder Pump Installation Parts & Procedures

Sketch of a sewage grinder pump partsArticle Contents


Parts of a Sewage Grinder Pump System

The sewage grinder pump is housed in a plastic or steel reservoir which receives waste from the bathroom or other plumbing fixtures it serves.

When a float inside the reservoir indicates that the sewage level has reached a high level in the reservoir, the float turns on the grinder pump which grinds and pumps away the waste.

The pump shown at the top of this page is a sewage grinder pump which grinds the waste and pumps the solid/liquid measure to the building main drain. At left the sewage grinder pump parts include:

  1. Sewage Grinder tank (this is an Environment One Grinder Pump System)
  2. Lifting eyes for removing the assembly (the circles at the mid-tank seam)
  3. Electrical wiring leads for the grinder pump and septic pump alarm
  4. Electrical disconnect box for the grinder pump system
  5. Drain inlet: 4" PVC tank inlet for connection to building drains served by the pump
  6. Sewage pump tank vent. The sewage grinder tank must be vented either directly or through the inlet pipe and within 4 ft. of the tank to a building plumbing vent stack
  7. Drain inlet gravity service line - wastewater flows into the tank by gravity from this line.
  8. Ground sewage outlet: 1 1/4" male pipe thread discharge outlet (the small diameter pipe leaving the tank at top right and passing through the foundation wall)
  9. Concrete septic pumping tank anchor (900 pounds, or about 6 cu .ft. of concrete to prevent the tank from floating up out of the ground)
  10. Sewage Pumping Tank bedding gravel, 6" deep of rounded pea gravel.

(Sketch is from the Environment One Low Pressure Sewer Systems Grinder Pump catalog.)

Sewage or Septic Grinder pumps grind the solid waste entering the system, then pump it to the building drain. The building sewer drain then carries this mixture by gravity (a gravity main system) or by pump pressure (a forced main) to its destination at a septic tank and drainfield system or to a municipal sewer. Septic grinders are intended for use at residential or small commercial locations.

Because the waste is ground and pumped under pressure, these pumps can lift high distances, say from a basement floor even to a street sewer which may be uphill from the home, or to a high pressure sewer main that may be located some distance away.

For example, we inspected a summer camp community which used this force-main sewer system to move waste from buildings across a site covering several acres to a common septic system.

Small sewage ejectors are for homes and commercial applications where toilet usage and wastewater loads are modest.

A typical home sewage grinder pump uses a 1/3 to two horsepower electric motor which powers a grinder mechanism that grinds the waste, and an actual sewage waste pump which moves the ground sewage/wastewater mixture up a riser pipe to its destination: the building main sewer drain, where the wastewater is carried to a septic tank or to a community sewer line.

Sewage Pump Installation Details

Sewage grinder pump installation details, adapted from Zoeller pumps (C) Zoeller.comSewage / Septic Grinder Pump Installation Tips adapted from Zoeller Pumps & other sources & installation manuals: (See REFERENCES)

[Click to enlarge any image]

Sewage, Grinder, Septic & Efflulent Pump or Sump Pump Vent Opening Requirements & Turbulence

Zoeller sump or sewage pump installation vent opening details - InspectApedia adapted from Zoeller see The weep hole or sewage / effluent / ejector pump discharge line vent hole permits purging of air trapped in the discharge line at the start of a pump-on cycle. This vent prevents discharge line clogging and pump seal failures. Note that some grinder pumps include a vent opening right in the pump housing oppsite the float control. Even so, the vent in the discharge line is still required.

At bottom left of our illustration you can see the weep hole vent location for a typical grinder or effluent discharge pump discharge line marked and circled in blue.

[Click to enlarge any image]

Zoeller Pump and some other sewage pump manufacturers provide a combined union/check valve, [For example Zoeller's "Unicheck" valve]. Zoeller notes that with this valve is installed, the installer must drill a 3/16" (5mm) vent opening in the discharge line at a height even with the top of the pump. This discharge line must be cleaned periodically. You should see water squirting out of this opening when the pump is running.

The following excerpt is from Zoeller (2009) cited at REFERENCES

It is necessary that all submersible sump, effluent, and sewage pumps capable of handling various sizes of solid waste be of the bottom intake design to reduce clogging and seal failures.

If a check valve is incorporated in the installation, a vent hole (approx. 3/16") must be drilled in the discharge pipe below the check valve and pit cover to purge the unit of trapped air. Trapped air is caused by agitation and/or a dry basin.

Vent hole should be checked periodically for clogging. The 50 or 90 Series [Zoeller] pumps have a vent located in the pump housing opposite the float, adjacent to a housing lug, but an additional vent hole is recommended.

Watch out: Zoeller also issues this warning about use of vent holes on high-head sump or ejector pump installations:

The vent hole on a High Head application may cause too much turbulence. You may not want to drill one. If you choose not to drill a vent hole, be sure the pump case and impeller is covered with liquid before connecting the pipe to the check valve and no inlet carries air to the pump intake.

NOTE: THE [sewage, sump, or effluent pump vent] HOLE MUST ALSO BE BELOW THE BASIN COVER AND CLEANED PERIODICALLY. Water stream will be visible from this hole during pump run period. - Zoeller (2009)

Set the Sewage Ejector Pump Float Control Switch

Little Giant sewage pump and float switch

A float control switch is used to turn the sewage pump on and off. Be sure to set the switch position and to adjust the float positions that turn the pump on and off in accordance with the manufacturer's installation instructions.

Most float switches used on sump pumps and sewage ejector pumps are set to turn the pump on well before the holding chamber is at risk of flooding the building, and to turn the sewage pump off while the pump body or at least the pump impeller assembly is still below the liquid level in the chamber.

See more illustrations of types of sewage ejector float control switches and notes on float position setting found at SEWAGE PUMP DAMAGE & REPAIR.

The sewage pump shown at left is a Little Giant model, available from [4] and other plumbing suppliers.

Guide to Non-Clogging Sewer Pumps

Non-clogging sewer pumps, or "non-clogs", are similar in principle to the grinder pumps discussed above, but they have more capacity, and can move solids up to 4" in diameter to a sewer main or waste handling system.

Non-clogging pumps are used in some residential installations but more often in commercial or community systems or

Septic Pump Articles


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