Why is my septic system backing up?

A backup in a septic system is a troubling event that homeowners would ideally like to avoid. Aside from being just plain gross, it can be expensive if it causes damage to flooring, walls, and furniture, and septic water contains billions of potentially harmful pathogens you definitely don’t want inside your home.

Here are 11 reasons why your septic system might be backing up:

1. Full Septic Tank: The most common reason for a septic backup is a tank that needs to be cleared out, either through pumping or with a proper tank cleaning treatment. Over time, solids settle at the bottom of the tank, forming a sludge layer. If the tank isn’t pumped regularly, this sludge layer can grow until it reaches the outlet pipe, allowing solids to flow into the drain field and clog it. When the drain field is clogged, water has nowhere else to go but backward.
2. Clogged Outlet Baffle or Filter: Many septic tanks have filters or baffles at the outlet to prevent solids from entering the drain field. If these become clogged, wastewater can’t flow out of the tank, leading to a backup.
3. Blocked Pipe Between House and Tank: If the pipe that connects the house to the septic tank gets blocked (due to objects, buildup, or tree roots), wastewater can’t flow into the tank, causing a backup into the house.
4. Failed Drain Field: As mentioned in our previous post about failed drain fields, several issues can cause a drain field to fail, such as clogging, compacted soil, tree root intrusion, or being overloaded with water. A failed drain field can’t absorb and disperse wastewater, leading it to back up into the septic tank and potentially the house.
5. High Water Table: After prolonged heavy rainfall or flooding, the water table might rise to a level close to your drain field. This can reduce the drain field’s ability to disperse wastewater, leading to a potential backup.
6. Inappropriate Disposal Practices: Flushing non-biodegradable items (e.g., diapers, wipes, feminine hygiene products) or pouring fats, oils, and grease down drains can lead to blockages in the system.
7. Broken or Damaged Pipes: Any damage to the pipes, whether from ground movement, tree root intrusion, or other causes, can prevent wastewater from flowing correctly, leading to backups.
8. Chemicals: Pouring harsh chemicals or solvents down the drain can kill the beneficial bacteria in the septic tank that help break down waste. Without these bacteria, the tank can fill up faster and potentially back up.
9. System Age and Neglect: Older septic systems that haven’t been well-maintained with occasional pumping and proper septic maintenance treatments are more prone to backups due to wear and tear and accumulated issues over the years.
10. Lack of Venting: Venting issues in the plumbing system can cause slow draining and backups. Vents ensure that wastewater flows smoothly out to the septic tank.
11. Heavy Water Use: Using a large amount of water in a short time frame can overload a septic system. Examples include multiple laundry loads in a day or several simultaneous showers.

Regular maintenance, including periodic drain field cleaning, maintenance, and inspection, is crucial to prevent septic system backups and extend the life of your septic system. If you experience a backup, it’s important to call a septic system professional to address the issue and prevent further damage.