Signs your septic system is failing

Septic systems usually warn you before they fail completely. The earlier you act, the more likely the fix is a pump-out or a cracked baffle rather than a new drainfield. Here are the signs EPA lists, roughly in the order homeowners notice them, with what each one often points to.

Inside the house

• Slow drains everywhere. One slow sink is usually a clog in that pipe. Several fixtures draining slowly at once point to the main line, the tank, or the drainfield.
• Gurgling in the plumbing. Air being pushed through water in the pipes can mean the line or tank is backing up.
• Sewage backing up into the lowest drains, such as a basement floor drain or a ground-floor shower. This needs attention the same day.

In the yard

• Standing water or damp, spongy spots over the tank or drainfield, especially when it hasn't rained.
• Sewage odors around the tank or drainfield.
• Bright green, lush grass over the drainfield, even in dry weather. Effluent is surfacing and fertilizing the grass.
• Algae blooms in a nearby pond or lake.

In the water

EPA also lists high levels of nitrates or coliform bacteria in drinking water wells as a sign of septic trouble, whether it's yours or a neighbor's. If your well test suddenly shows bacteria or rising nitrate, get the septic system checked as well as the well.

Not every smell means failure

EPA notes that odors can come from the plumbing vent on the roof, which is a normal part of the system. Vents can clog with leaves or freeze in a cold snap, and wind can push the smell down into the yard. A vent problem is a far cheaper fix than a failing system, so it's worth checking first.

What to do first

1. Cut water use right away. Hold off on laundry, long showers, and the dishwasher.
2. Call a licensed septic service provider to locate and inspect the tank. If it's full, pumping may give immediate relief. Ask them to check the baffles, the effluent filter, and the pipe to the drainfield.
3. Keep people and pets away from surfacing sewage, and avoid contact with it. It can carry harmful pathogens.
4. Call your local health department if sewage is surfacing or backing up. Repairs usually need a permit.

Why pumping doesn't always fix it

Penn State Extension explains that by the time sewage backs up into a house, the drainfield soil is often clogged with a nearly impermeable layer called a biomat. Pumping the tank won't remove it. Sometimes resting the drainfield lets the biomat break down. Other times the drainfield has to be repaired or replaced. The best protection is prevention: regular inspections and pumping, as EPA recommends. See our pumping calculator.

Common causes

EPA says most malfunctions come from inappropriate design or poor maintenance. That includes systems installed in unsuitable soil or where groundwater is high, tanks that were never pumped so solids migrated to the drainfield, too much water, and physical damage from vehicles or tree roots. Knowing the cause helps you avoid a repeat after repairs.