“I need a grinder pump.” is a call we often get from plumbers when in most cases what they really need is a sewage pump. Some people think that all sewage pumps grind up the waste when in fact they pump the 2″ solids by velocity with either a “vortex” or “deep vane” impeller. The “deep vane” impeller will break up the sewage, but by no means will it be ground up.
A true grinder pump will actually chop and shred the sewage and pump it through a 1-1/4″ pipe. These are powerful pumps, usually 1 or 2 horse power and 230 volt depending upon the brand, they in fact are capable of pumping the waste for over a mile to a gravity sewer.
A sewage pump for most residential applications is either a 4/10 or ½ horse power and 115 volt, they have a 2″ or 3″ discharge and they will , in most cases, only need to pump up to 15 feet of lift to a gravity sewer.
There is a huge difference in the replacement cost of the grinder pumps, which can have a $2,000.00 to $3,000.00 retail price depending upon installation and labor. The replacement cost of a sewage pump could be in the $400.00 to $600.00 price range depending upon installation and labor.
The typical sewage pump installation we see is where there is a bathroom group of fixtures in a lower level that drains and collects into a basin and gets pumped to a gravity line which is connected to the gravity sewer or septic system. The sewage pump is usually installed in that 18″ x 30″ or larger basin with a sealed cover, sealed vent and discharge, and a check valve to prevent backflow from the gravity sewer.
A grinder pump is usually used in jobs where the gravity sewer is a long distance from the home, or there is a high vertical lift of 30′ or more, and in a lot if situations, is part of a pressure sewer system. There are in fact whole subdivisions where all the homes have grinder pumps. These have sewer laterals that are 1-1/4″ with sewer mains being 2″. The ground up waste is pumped to a municipal sewer station for treatment.
Some grinder systems are installed outdoors in a “Lift Station” or indoors in a 24″ or 30″ diameter basin with a sealed cover, sealed vent and discharge, and a check valve. Most grinder pumps have a control panel with a built in alarm because they are serving the whole house.
In my opinion, all sewage pump systems should be equipped with an alarm that is properly set and tested. This will warn you to stop using your plumbing and allow you to call your plumbing service technician before you flood.
If you have questions, we have answers. Please feel free to call us for pump sizing and unique pumping situations.