They often create a foreign type of bacteria which if pushed out into the drainfield can cause premature failure of the system. Driving cars, trucks and other heavy vehicles should never travel over a septic or drainfield system. Driving household lawnmowers over septic and drainfield systems are on the other hand, ok. Normally a 16x16 or 24x24 manhole plug will be over the inlet and outlet ends of the tank and usually very accessable, however for homes over 30 years old there may be a strip lid style cover on the septic tank which requires specific location. Keep grease and fats out of drain lines and septic tank.
Dispose table scrapes before washing dishes, pots and pans.
Keep trees and their root systems away from the septic and drainfield system. Never build any structures over your septic tank or drainfield. Yes, all septic system repairs and drainfield replacements require permit from the Department of Health and must be conducted by a licensed septic tank contractor. However, pumping your septic tank does not require a permit. Yellow grass over the drainfield area, where normally plush and green.