Duplex septic pump installation Installation Guide for Duplex Septic Pump & Sewage Pumping Installations

  • SEPTIC PUMP DUPLEX DESIGNS - CONTENTS: alternating septic pump compared with reserve backup septic or sewage pump - Septic tank pumps, septic grinder pumps, septic effluent pumps installed in duplex alternating operation sequence or in wastewater level backup design.
  • POST a QUESTION or READ FAQs about duplexing or doubling septic and sewage ejector pumps
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Duplex septic pumps or sump pumps:

For critical systems such as a sewage system that depends on pumps for operation or a building that depends on sump pumps to keep water out of a low area, duplexing the pumps along with appropriate controls and periodic testing is an important step.

This article describes the reasons & methods for installing duplex versions of septic pumps, septic sump pumps, sewage ejector Pumps, septic grinder pumps, & pumps in sewage pumping stations.

Advice is given for septic tank effluent or sewage pump selection and use.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Duplex Septic Pump System Designs

Septic pumps used for pumping air in aeration systems and septic pumps used to move effluent in a drip dispersion system are discussed under the appropriate septic system type which are outlined at SEPTIC SYSTEM DESIGN ALTERNATIVES.

.There are two common pump-pair or duplex septic grinder pump system setups. Either of these is found at municipal lift stations and similar installations.

1. Alternating septic pumps: two septic pumps alternate, taking turns running - I prefer this method as you are spreading the wear over two pumps and you'll know when one fails and have a chance to repair it.

The two sewage grinder pumps are installed at the same location but are wired so that the pumps take turns, first one, and next cycle the other pump is turned on by the float switch.

However this system lacks the ability to handle surges in wastewater load unless additional controls and wiring are installed to make the pump also come on in response to high waste levels such as in the reserve septic backup design discussed next.

2. Reserve septic backup design: the backup septic pump never runs unless the primary septic pump has failed or is overloaded. A simple installation provides a pump control float switch that turns on the backup pump only when effluent or sewage in the pumping chamber reaches a level above that normally handled by the primary septic pump.

This approach provides both pump backup and the ability to handle surges in sewage loads on the system.

Handling surge loads on the septic system: A duplex septic pump system in which the second pump can come on as effluent level rises in the pumping chamber handles either unusual flows into the system (uncommon) or the case where the 1st pump is broken. I don't like this setup as much as we're never testing pump #2 until the very day it's absolutely needed.

Septic Pump controls for two-pump duplexed septic systems are produced by several manufacturers including Anchor Scientific, Aquawarx (control panels), B/W Controls, Orenco, Rhombus, SJ Electro, and CSI.

Reliability requirements define when a duplex sewage grinder pump or septic pump system is appropriate

Wile single grinder pump systems are often installed to support an extra basement bathroom, where a sewage pump is handling an entire home or larger facility, duplex septic pumping systems (shown in the photo at the top of this page) are preferable for their greater reliability. There are two principal advantages of a two-pump septic system:

  1. Septic system reliability: If either sewage pump fails the second unit can keep the building's plumbing system operating while the failed pump is repaired.

  2. Handling surge loads in a septic system: If the building is one which experiences surges in wastewater loading, the duplex sewage pump design option #2 described below can handle this extra wastewater load without a system backup.

(Remember that in a power outage your pump system will not work unless you've provided backup power.)

Inspecting Duplex Septic Pump Systems

Additional details about the installation of sewage grinder or septic pumps and how to inspect them can be found at Sewage Ejector Pump Grinder Pump . Beyond those suggestions, when inspecting a duplex septic pump system, remember to assure that both pumps are in working condition and that the switch between them is functioning. Simply turn off power to one pump to confirm that the second one will operate, and vice versa.

Duplex Septic Pump System Alarms

Duplex septic pump alarm installation

A duplex septic pump system is installed where septic and plumbing system reliability are very important. That same requirement makes it important for the building occupants or maintenance staff to know if one of the pumps has failed, so that a repair can be ordered before both pumps stop working.

A duplex septic pump alarm system accomplishes this function and can also diagnose the system by indicating which pump has stopped operating.

Here is a photo of a typical alarm system for a duplex sewage grinder pump installation.

We discuss septic system alarms in more detail at Septic Pump Alarm Systems

This duplex septic pump article is part of our series: SEPTIC SYSTEM INSPECTION & MAINTENANCE COURSE an online book on septic systems


Septic Pump Articles


Continue reading at SEPTIC PUMP INSPECTION & MAINTENANCE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see WATER ENTRY in BUILDINGS for the diagnosis & cure of wet basements or crawl spaces.

Suggested citation for this web page

SEPTIC PUMP DUPLEX DESIGNS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Questions & answers or comments about duplexing or doubling septic and sewage ejector pumps

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman