Inspect the sludge level of your septic tank. If the tank has too much sludge it can result in backups into the home or clogging of the lines to the septic field. Open the access port and lower a long pole or rod into the tank. Note when you feel the pole strike the sludge and then the bottom of the tank. If the tank's interior is more than a third filled with sludge, it should be pumped out.
Clean the interior of the tank. If poisonous chemicals have entered the tank they may have killed the bacteria in the tank. This bacteria is necessary to break down the solid waste into a liquid form. Once the tank is pumped and cleaned the system will begin to recover. The waste products entering the septic tank naturally contain the bacteria needed to process the waste.
Clear the pipes of roots and other clogs. Open the distribution box and temporarily block the outlet ports with a fine wire mesh or screen. Insert the cable from the plumbing router into the access port of your piping system. Slowly feed more cable into the pipe until the end of the cable has reached the distribution box. If you have an exceptionally long section of pipe you may have the enter the pipe from multiple access points. Debris from any clogs will gather in the distribution box. Remove all debris and trash, then remove the screen and re-seal and bury the distribution box.
Route any drain lines away from your septic system. Direct any downspouts from your roof gutters so they will drain away from your septic system, especially the field lines. If possible, direct any runoff water away from your field lines as well. The less water that enters your septic system, the healthier your system will be.