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Learn more about the grinder pump system on your property

Each and everyday of the year, millions of gallons of wastewater leaves your home or business to be treated and reclaimed into the environment.  The trek to get treated includes hundreds of miles of sewer mains and pipes that ulimately lead to one of the County's seven water reclamation facilities.  For the vast majority of customers, wastewater leaves their homes and travels by gravity to the sewer main in the middle of the street.  Unfortunately, it is not possible for wastewater to flow the entire way to the water reclamation facilities. by gravity.  When the wastewater reaches the end of the gravity main, one of the County's 257 sewer pump stations will transfer it to a pressurized force main.  These force mains push the wastewater along the final leg of the journey until it reaches the treatment plant. 
Homes that sit below the grade of the sewer main and can not use gravity pipes for the flow of wastewater need grinder pumps.  Grinder pumps are economical solutions for customers in these particular areas that could not otherwise connect to the publilc sewer system.  They are low-pressure sewage systems that grinds the sewage from your home (much like a garbage disposal) and pushes it through small plastic pipes to the larger lines in the street.
Collecting the wastewater that exits your home
Your sewage grinder pump is housed by an underground sewage holding tank on your property.  The tank temporarily contains the wastewater that exits your home.  These tanks are made of extremely reliable fiberglass or high density polyethylene (HDPE) plastic to protect against damage and leaks.  The tank cover is round and is the only part that shows above the ground. 
Grinding uphill
Just like most public sewer customers, the wastewater exiting a home served by a grinder pump flows out of the home by gravity.  However,  the gravity line can only take the wastewater as far as the holding tank.  Once the wastewater is contained in the holding tank, the process of pushing it uphill to the gravity main in the middle of your street begins.
  1. Wastewater fows from  your home by gravity to an underground holding tank.
  2. Pumps turn on at a capacity of 20 gallons to grind, condense and force wastewater out of tank to a County pressure sewer line.
  3. Wastewater is then pushed uphill by pressure to the County sewer main located in your street.
  4. Wastewater now flows by gravity to a pump station.
  5. Pump station transfers wastewater to force main and the final push by pressure to treatment plant. 
The grinder pump is powered by electricity and is connected to the electric service lines usually at a panel box near your electric meter on the outside wall of your home. However some are located on a panel inside the home. Grinder pump electricity charges are estimated to be less than a dollar per month and will be included on your monthly electric bill. The cost of electricity is paid by you, not the county.
Electrical power and alarm wires are buried under the ground between the control panel and the tank.  Before digging in the area, call to have a technician locate the lines.
Older grinder models have a small breather vent located on the side of the tank, just below the cover.  It is important to keep this vent open and free debris, such as mulch or grass, for the unit to remain operational. It is also helpful to have the ground sloped away from the tank so water will not pool and enter the vent rendering the unit inoperable.
If your home is new construction and less than one year old, then your grinder pump is still under warranty through your builder. Any problems you experience with the grinder pump system during that period should be referred to the builder or his representative.
With your cooperation, your low-pressure system will provide many years of safe, reliable service.  Please take a few moments to read the following information to insure the proper functioning of your pump.
If the Alarm Sounds…
If there is a grinder pump failure, the tank which contains the pump will become too full. An alarm horn and light located in the alarm box on the outside of your home will automatically turn on. You should…
  • Discontinue water use to prevent overflows.
  • Turn off the alarm by depressing the alarm light on the front of the alarm box. The alarm horn should silence but the light will remain on until the grinder pump is repaired.
  • Wait fifteen minutes before taking further action. A high level of water usage will sometimes cause the alarm to come on. This situation is self-correcting.  If the pump is operating correctly, the wet well will automatically be pumped down and the alarm light will turn off.
  • If the alarm light is still on after fifteen minutes, call our 24-hour emergency dispatcher at (410) 222-8400. The dispatcher will notify you if your system is privately maintained, in which case, you must contact a plumber or the supplier of the pump, Freemier and Associates at (410) 768-8500.
  • Never attempt to open the tank cover or the electrical panel box. CAUTION: Electrical shock or damage to the system may occur. 
County emergency crews are on duty 24 hours a day, seven days a week and will respond promptly.
Protect Your Pump
The grinder pump can handle any wastewater that is normally discharged to the sewer from the kitchen, bathroom or laundry. Some chemicals and materials may cause operating problems or safety hazards. It is advisable to check labels on chemicals prior to their disposal. Never connect a sump pump to the grinder pump.
CAUTION: Never put any of the following materials into sinks, toilets or drains:
  • Glass, metal, wood, seafood shells
  • Papers, socks, rags or cloth of any kind
  • Plastic objects (toys, eating utensils, etc.)
  • Any strong chemical, toxic, caustic, or poisonous substance
  • Degreasing solvents
  • Any explosive or flammable material
  • Gasoline, kerosene, fuel oil, paint thinner, and anti-freeze
  • Lubricating oil or grease
  • Cooking fat (lard, oil, grease)
  • Hair clippings
  • Coffee Beans
  • Egg Shells
These materials may clog your home system or create unsafe conditions in your lines and tank.
In case of Power Failure
If there is a power failure which affects your home, your grinder pump will also experience a loss of power and not be able to operate. The grinder pump tank has a certain amount of holding capacity, but interior water use should be severely limited until power has been restored.
While on Vacation
If you have been away from home for more than seven days, the following steps should be taken to minimize any stagnating odors.
First, run water from an inside tap long enough for the grinder pump to begin working. After the pump turns on, turn the water off. The grinder pump will run until the tank is empty and will shut off. This process will cleanse the pump and leave it filled with a minimum of clean water. Always leave the electrical power on. This allows the heating element inside the pump to operate which helps eliminate condensation and freezing.
By following these guidelines, you can ensure that your low-pressure system will provide many years of safe, reliable service.



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Anne Arundel County, Maryland. 44 Calvert Street, Annapolis, Maryland 21401 | Tele: (410) 222-7000