Grinder Pumps

What is a grinder pump?

A type of pump used to grind up sewage solids from a commercial building, an individual household, or a group of homes. They are similar to chopper pumps in that their primary purpose is to make solids-laden water more manageable. But while chopper pumps usually operate within a municipal sewage treatment plant or in an industrial waste processing facility, grinder pumps are typically owned by private individuals or small communities.

The pump is used to grind the solids in a building’s outgoing sewage and pump it to a larger sewage collection site, where it is combined with sewage being sent from other homes and pumped to the sewage treatment plant in a sewage lift station. The principal advantage is that the sewage travels from the original home or building to the central sewage collection point and lift station under pressure, rather than by gravity drain from the homes. This means that homes located in remote locations, or where the topography is not conducive to gravity drain to central collection systems (such as hilly areas) may still feed sewage to the central collection system. In addition, the sewage line from the grinder pump may be a small size (typically 1.5 inches), whereas a gravity drain sewer line must be 4 inches or 6 inches. This saves money on the sewage collection infrastructure. 

Another benefit is that because the sewage is pressurized, it can be pumped a long distance under pressure to the central sewage treatment plant or to a sewage lift station, rather than being required to drain by gravity.

Grinder pumps are most commonly found in new developments where a gravity drain tie-in to the central collection system hasn’t yet been built, or cannot be built due to limitations of the topography. For example, they are often located in vacation cottages in the country or on lakes.

How do they work?

There are two main types, both designed to move outgoing sewage to an end location where it can be processed. They can be centrifugal or positive displacement pumps. Both versions contain grinding teeth as part of the pump impeller or rotor, which grinds the wastewater before sending it through the pump.

A centrifugal configuration is a submersible pump, with the motor operating submerged in the building sewage collection sump. The submersible motor is attached to an impeller, which has grinding teeth on the front or back sides. Thus, the impeller grinds the sewage, as well as passing it through the volute of the pump to build up pressure.

Positive displacement types are driven by a submersible motor, but rrather than driving an impeller, the submersible motor drives a progressing cavity type rotor as it moves inside its stator.

Here are a few grinder pump manufacturers to consider.

Other related Pump Types include: wastewater pumps, utility pumps, water pump.

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