A common myth is that septic tank additives will break down the sludge in your tank so that it never needs to be pumped. This is totally false. Septic tank additives are unnecessary since you contain everything needed to inoculate your septic tank with bacteria.

  
   If the additive claims to contain the bacteria you need to augment your septic tank's bacterial load remember that milk carton you left out on the counter a while back. After leaving the half-full carton on the counter all day, it was bulging. In fact, it was teeming with bacteria that had generated on their own when the conditions were suitable. If your septic tank could handle more bacteria, it would make them. Adding a little container of this or that is not going to help shift the balance of bacteria in your tank. If your septic system professional says you have a sick tank, have the tank pumped and start again.
   In Washington state, makers of septic tank additives are required to prove the products do not harm the environment. They are not, however, required to prove they are effective.