The best way to keep a septic tank clean is to hire a local septic tank cleaner to inspect and pump the septic tank every three to five years. Be sure to only flush human waste and toilet paper down the toilet, and don’t pour grease, oil, fats, coffee grounds, or food scraps into your drains.

Septic tanks appear full after pumping because the liquid levels have returned to normal. If you can see the pipe, the tank is empty. However, heavy rain can cause septic tanks to fill faster than normal. You might also have leaky pipes or faucets, causing extra water to drip down the drains and into the septic tank.

Your septic tank naturally contains the beneficial bacteria it needs to function, so you typically don't need to add more. However, if you wish to replenish the bacteria, you can use natural methods. For example, you can add three overripe tomatoes to your garbage disposal or flush 1/4 ounce of active yeast down the toilet every three months. While store-bought septic enzymes and chemicals are available, many experts consider them unnecessary and potentially harmful. The most effective way to maintain a healthy bacteria population is to avoid using chemical drain cleaners, which can kill the good bacteria in your system.

Although cesspits may be necessary depending on your main sewage system access or nearby soil quality, they carry a few drawbacks. Cesspools require regular emptying and have relatively high maintenance and pumping costs. Certain areas also disallow the use of cesspools and may require you to cover the cost of existing cesspools to be converted into septic tanks.