Septic backing up into the house

Sewage coming up through the lowest drain in the house (a basement floor drain, a downstairs shower, a ground-floor tub) means wastewater can't get out of the house fast enough. On a septic system, that's either a blockage in the pipe on its way to the tank, a tank that's too full to take more, or a drain field that's stopped accepting water and is backing everything up behind it. All three need a septic contractor, but what you do in the next hour still matters.

The first hour

1. Stop using water. No flushing, no showers, no dishwasher, no laundry. Every gallon you send has to go somewhere, and right now that's onto your floor.
2. Keep people and pets away from it. The EPA warns that sewage may contain harmful pathogens. Don't wade through it in socks.
3. Call for help. The number on this page goes to a local septic contractor. Say whether it's coming up in one drain or several, and when the tank was last pumped if you know.
4. If you can, find the cleanout and the tank lids. It saves time when the truck shows up.

Narrowing down the cause

What the contractor will usually do

First they'll check the level in the tank. If the tank is low and the house is backing up, the blockage is between the house and the tank, so it's a line or inlet baffle problem. If the tank is brimming, they'll pump it, which often gets the house usable again right away, and then look at why it filled. A tank that refills quickly from the field side after pumping points to a field that's saturated or failing, and that turns into a repair conversation.

Cleaning up safely

The EPA's guidance for a sewage backup inside the home:

• Wear protective gear, including long rubber gloves and something to shield your face from splashes.
• Clean and then disinfect hard surfaces with a solution of 10 percent household bleach and 90 percent water.
• Wash every tool and piece of clothing you used.
• Keep the area out of use until it has been dry for at least 24 hours.

Soaked carpet, drywall and insulation generally have to come out, and a large backup may call for a cleanup company. Check with your homeowner's insurance about coverage, since policies differ.

Keeping it from happening again

Most backups trace back to one of a few habits: a tank left too long between pumpings, wipes and grease going down the drains, or too much water at once. The EPA says only human waste and toilet paper belong in the toilet; wipes, grease, paper towels and the like stay out. Our pumping schedule guide helps you set a reminder that fits your household.

Good questions

Can I use a chemical drain opener on a septic backup?

The EPA advises against chemical drain openers on septic systems and suggests boiling water or a drain snake for ordinary clogs. When sewage is backing up through several drains, a drain opener will not fix a full tank or a failed field.

Is a septic backup an emergency?

If sewage is coming into living space, treat it as urgent: stop using water and get a contractor out. Ask about any after-hours charge when you call.