The most common maintenance on a septic tank is periodically they will need to be pumped out. The more solids that get added into the tank the faster the sludge will build up. Garbage disposals and people using the toilet as a garbage can lead to a lot of sludge build up. Avoid putting anything that can’t or wont decompose easily into your septic tank, Only put organics and human body waste down the drain. The scum level builds up fastest when people pour grease down the drain. Grease will eventually block your entire system if it is not kept in check. Do not pour grease down the drain, It is not good for the septic system or for a municipal sewer system just don’t do it !