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

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.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Guide to Sewage Grinder Pump Installation Parts & Procedures

Sketch of a sewage grinder pump parts

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) InspectApedia.com Zoeller.com

[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 zoeller.com 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 atReferences or Citations

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 plumbingsupply.com [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

at SEWAGE PUMPING STATIONS.

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-07-13 - by (mod) -

John

Got a sewage ejector station event that you refer to is usually and air inlet valve not an air outlet valve so it's correct that you should not smell any sewer gas at that location.

It would be diagnostic to determine if the sewage smell that you are observing is coming down from the rooftop vent at is stronger Outdoors or if you are smelling it stronger inside which would suggest there may be a leak in a vent pipe or drain system in the building.

On 2020-07-13 by John

I have a small basement Holding tank below grade. The sewage is pumped up into the Ceptic tank.

There is a small vent pipe on the tank which opens into the basement. No smell comes from the vent pipe. However, whenever we shower anywhere in the house, we smell the sewage from the rooftop vent pipe. We tried extending the vent pipe but that doesn’t work. What could be wrong?

On 2020-05-30 - by (mod) -

Anon

The pump inlet is above the chamber floor, usually provided by the pump base design or feet

On 2020-05-30 by Anonymous

Does the grinder pump set on the basin floor or is the pump suspended a few inches above the floor ?

On 2020-05-08 by Anonymous

y does the pump shake wildly

On 2018-02-09 - by (mod) -

Bob

IN a residential plumbing drain system that's connected to a private septic tank and absorption field, a septic pump, probably a sewage ejector pump if the right pump was selected, moves waste out to the septic tank.

If your property includes a physically separate graywater disposal system (like a seepage pit that's separate from the septic system) would the graywater be pumped to that different destination.

If you don't know if your graywater is being sent to a separate destination and if you do not have a septic/graywater system drawing and plan, and if you can't find one at your local building and zoning department, then you'd have to follow the pipes - which is a devil of a job if the pipes and ground are frozen.

On 2018-02-0 by Bob

I have septic pump inside of my house. Is the 2" pipe with gray water , pumped out directly to the field ? , or it is routed through the tank. It's freezing , and I need to know how it is routed under the ground.

On 2016-05-03 - by (mod) -

See AIR ADMITTANCE VALVES AAVs at https://inspectapedia.com/plumbing/Plumbing_Vent_Definitions.php#AAV

On 2016-05-02 by dman178

I think I need to offer some more information: The location of the new toilet in my friend's DIY remodel is not near an existing vent (over 15 ft), and venting up through the roof isn't an option.

The reason he believes he needs the pump is that the soil line is too tight against the top of the crawl space to allow a Studor valve to be installed at the minimum required height.

The solution that was posed to me was to put the pump/basin in the crawl space under the toilet with a Studor valve mounted to the basin lid (36" above the lid, actually) to provide venting for the pump.

Does this sound plausible? Someone else suggested that the one-way venting from the Studor valve could cause methane to build up and risk rupturing the basin. I'm not on the hook for any of this, but I want to offer the best advice possible. Thanks for your help.

On 2016-05-02 - by (mod) -

dm

As long as it's properly supported against tipping, and as long as the elevations work with respect to drainage in to the unit, it does not have to be set into the ground.

On 2016-05-02 by dman278

I'm looking to install a septic grinder pump in a 5' high crawl space with concrete floor. Does the basin have to go into the ground or can it sit on the concrete floor?


...

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