Avoid chemicals. Synthetic cleaners and anti-bacterial chemicals kill off the useful bacteria required by the system to rapidly break down and naturally decompose organic substances in your septic tank. This breakdown process is an essential part of a healthy septic tank system.
When decomposition does not occur because of continual chemical interference, your system will smell. Normally, you should not be able to smell a working septic tank. Chemicals include medicines which should not be disposed of by flushing down the toilet.