You can help maintain your tank by keeping it clean. Never flush anything but toilet paper, pee and poop—even if you think it’s biodegradable! Don’t dump any chemicals down the drain or flush anything that isn't toilet paper, pee or poop. Besides keeping your tank clean, there are other ways to prevent problems with your septic system: Use enough water to fill the bowl more than halfway before each use so that wastewater has less time to sit in the pipes. Don’t put grease down the drain or send food scraps through garbage disposals (they will clog up). Instead, compost them in an outdoor bin made for composting purposes or throw them away in a plastic bag in your trashcan (not regular garbage).