Problems

• Adding extra solid waste, like ground up food from a garbage disposal, raises the level of accumulated solids in the septic tank. Even if the solids don't rise high enough to clog the drainage holes at the top of the tank, the food flushes into the delicate drain field and creates blockages there, according to the American Ground Water Trust. This lowers the ability of the system to clean water properly before it returns to ground water stores. Contamination of local water sources or your well water could follow.
  
  

Larger Tank

• One way to work around the problem of the extra strain a garbage disposal causes includes adding a larger septic tank. Tanks with greater capacity hold more solid waste, according to Consumer Reports Greener Choices. When waste has room to settle at the bottom of the tank, it is less likely to wash into the drain field or clog the drainage ports. Replacing a smaller septic tank with a larger one is a serious and expensive procedure.
  
  

Frequent Pumping

• If you're convinced that you need to use a garbage disposal with your septic tank, be prepared to pump your septic tank twice as often or more, according to Laundry Alternative. All septic tanks require pumping out at regular intervals because you add solid waste to the tank just by using the toilet in your home. However, most tanks are sized by the number of people in the home and will last for at least 2 or 3 years between pumping. Extra solid waste from the garbage disposal drastically shortens this interval.
  
  

Local Laws

• Even if you want to pay to install a large septic tank or for more frequent pumping, local laws may not allow you to use a garbage disposal. A local building inspector or official with the health department can tell you the laws concerning septic tanks and disposals in the area, according to Consumer Reports Greener Choices. Many areas have strict rules on tank size or property boundaries to prevent you from affecting nearby water sources in case the extra solids cause the septic system to fail.