Sketch of a common sewage grinder pump used in a modern basement Maintenance Guide for Free Standing Septic Pumps and Sump Pumps

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Free standing sewage grinder pumps or septic pumps:

This article explains the differences between Sump Pumps, Sewage Ejector Pumps, Septic Grinder Pumps, Sewage Pumping Stations, & Septic Pump Alarms.

We discuss the vertical lift required for different types of sewage or septic pumps and the importance of matching pump capacity to the design requirements of the system.

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What is a Free-Standing Sewage Grinder Pump

A sewage grinder pump is about the same as the packaged on in-can sewage ejector pump discussed above, except that the grinder pump is a heavy-duty pump which, instead of being in a prepackaged container such as for use to install a single basement bathroom at a level below the building sewer outlet height, the grinder pump is installed right in a septic tank.

The free standing sewage grinder pump macerates sewage so that it can be pumped through a (usually smaller-diameter, perhaps 2") force main to an uphill septic tank or sewage pumping station or to a municipal sewer line, all of which are in this case located higher than the pumping location. Thus the need for the pump.

A non-clogging sewage pump used in the same application is designed to move larger solids, up to perhaps 4" in diameter, to a gravity drain.

The "septic pump in a can" or packaged septic grinder pump systems described at SEWAGE EJECTOR / GRINDER PUMPS have varying lift capacity depending on the pump horsepower, but these are generally less powerful than a submersible sewage pump.

Photo of a community sewage pumping stationWhere a lot of vertical lift is needed (where there is a large "head" pressure), a submersible sewage grinder or effluent pump will be used and will be installed at or near the bottom of the holding tank. Though we can't see the pumps in this photo - they are below the sewage level in this pumping chamber - that's what we'd expect to find installed in this municipal sewage lift station (which we discuss in more detail at SEPTIC PUMPING STATIONS).

If someone installs an ordinary dewatering sump pump to pump sewage they're opting for an inexpensive pump that is not going to last long at all because it's being misused and it's going to clog up. Using an ordinary dewatering sump pump to move septic effluent is making a similar, if not as completely egregious mistake.

If you are pumping only clarified septic system effluent out of a septic pumping chamber which itself is downstream from and separated from a septic tank which contains solids and floating scum, then your pump does not need to be a grinder pump. However even in this case I would avoid the common $100.00 (ballpark) common sump pump because it's unlikely that the pump will have the duty cycle and durability to give you a long term, reliable septic system operation.

The best design for any pumping system, solids to a tank or effluent to an elevated drainfield, is a duplex pump system so that you have a chance to keep a working house drain system even when a pump fails.


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FREE-STANDING GRINDER PUMPS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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