Septic Tank Backup Problems

Chris Deziel

A septic backup is cause for concern, because the remedy could require costly repair. It's just as possible, though, that when water starts going the wrong way, and your lower toilets and drains overflow, the cause is a simple clog.

A septic tank pump truck.

If you understand how your septic system works and keep a regular eye on it, a major problem won't catch you by surprise -- and you'll be able to head off most of those problems by dealing with minor ones.

Septic System Design

Your septic system is tailored for the size of your house and the topography of your property. The tank must be 10 feet from the house, but it's usually a little more than that, and it's buried deep enough to allow water to flow into it by gravity. Pipes from the tank lead to a drain field where the effluent gets naturally purified by soaking into the ground. If your property is sloped, and the drain field is on higher ground than the tank, a pump inside the tank transfers the effluent. There may also be a macerating pump in the house to transfer sewage to the tank, if the tank is higher than the waste outlet from the house.

Early Warning Signs

Backups that require major repairs usually take time to develop, and the telltale signs are out in the yard or in your plumbing system. Drain-field failure is the most serious septic problem that can develop, and by the time it has become acute, there may be standing water and sewer odors around the drainpipes. Before that happens, you may notice unusually lush grass and greenery, sometimes forming stripes over the drainage pipes -- the plants are feeding on effluent that isn't draining. In the house, slow flushing and draining over an extended period are both signs of an impending backup. The slowdown may be caused by roots in the pipes or by an overflowing tank.

Responding to a Backup

When the water begins overflowing in the house, it's too late for maintenance. If your systems employs pumps, one of the first things you should do is to check the electrical breakers to ensure the pumps have power. Next, check for clogs by plunging and snaking the lowest toilet in the house. Blockages the auger can't pass through indicate root-bound pipes, which usually requires professional help. If the auger passes through unimpeded, you need to locate the tank and check it. It may simply need pumping, but there may also be a more serious problem.

Checking the Tank

The water level in the tank should be just below the bottom of the inlet pipe -- if it's higher than that, and it has a pump, the pump probably needs servicing. If the system is gravity-fed, the tank may need pumping, and you can determine that yourself with a long stick, tape measure and rubber gloves. It's also possible that water is backing up from the drain field, and in that case diagnosis may require some excavation. The tightline, which is the pipe from the pump to the drain field, may have broken. In the worst case, the drain field itself is overflowing, but this problem may be not be too serious if it's caused by excessive rainfall or freezing temperatures.