Don't drive over your tank and drainfield or compact the soil in any way.
Don't dig around the tank or drainfield, or build anything over it, and don't cover it with a hard surface such as concrete or asphalt.
Don't plant anything over or near the drainfield except grass. Roots from nearby trees and shrubs may clog and damage the drain lines.
Don't use a garbage disposal, or at least limit its usage. Disposals increase solid loadings to your tank by about 50%, so you have to pump your tank more often than normally suggested. Don't use your toilet as a trash can or poison your system and the groundwater by pouring harmful chemicals and cleansers down the drain. Harsh chemicals can kill the bacteria that help purify your wastewater. See the list below for examples.
Don't put in a separate pipe to carry wash waters to a side ditch or the woods. This graywater contains germs that can spread disease. Use a laundry system.
Don't waste money on septic tank additives. The bacteria necessary to treat wastewater is naturally present in sewage. Additives can resuspend solids causing your drainfield to clog. Additives do not eliminate the need for routine pumping of your tank.
Don't allow backwash from home water softeners to enter the septic system.
Never enter a septic tank – toxic gases from the tank can kill. If your system develops problems, get advice from your county health department or a licensed septic tank contractor.