Septic Backup: $300 to $700 to Pump the Tank (HomeGuide)

National figures. Cleanup prices come from HomeGuide's sewage and sewer backup guides and rise with square footage and mold.

Is it an emergency? Septic backing up into the house

Sewage in the house is a health problem before it is a plumbing one. EPA says wastewater that backs up into the home may contain harmful pathogens, so avoid contact and call a septic service provider or the local health department.

• Keep people out. The CDC says to keep children and pets away from the area until cleanup is finished, and to wear rubber boots, rubber gloves and goggles if you have to go in.
• Treat cuts right away. Mass.gov says to immediately wash and disinfect any wound that touches sewage, and that people with weakened immune systems are at greater risk.
• Stay off the tank. Purdue Extension says never lean into or enter a septic tank, which can hold hydrogen sulfide and methane, and to keep flames and cigarettes away because methane is explosive.
• Call now: sewage coming out of a floor drain, tub, shower or toilet, or surfacing in the yard.
• This week: slow drains in every bathroom, gurgling, or damp spots over the tank with no sewage inside yet. These are on EPA's list of malfunction signs.
• Can wait for a plumber: one slow sink while every other drain runs normally. NC State lists slow drains not caused by old clogged pipes as the septic sign, so a single clog is usually a drain cleaning job.

How to tell if your septic tank is full

Angi lists the signs of a full septic tank as gurgling in toilets, drains or pipes, sewage or rotten-egg odors, drains that stay slow, pooled water over the tank or drain field, sewage backing up into tub, shower or basement drains, unusually thick green grass over the tank, and more flies around the drain field or tank lid.

A working tank always holds wastewater: EPA says it keeps it long enough for solids to settle into sludge while oil and grease rise into scum. So a septic tank full of water is normal; full of solids is not. EPA's rule of thumb is to pump when solids reach two-thirds of the tank volume, and more precisely when the bottom of the scum is within 6 inches of the outlet or the top of the sludge is within 12 inches of it. Measuring that means opening the tank, which Angi says a professional should do because of toxic and flammable gases. How often to schedule it is on the septic tank pumping page.

Why is my septic backing up into the house?

• The tank was not pumped. NC State calls lack of pumping a key cause of premature septic failure.
• A clogged outlet filter. Purdue Extension says you must clean the outlet filter periodically or sewage will back up into the home. HomeGuide prices a new effluent filter at $200 to $300.
• A failed inlet baffle. HomeGuide's baffle guide says it can show up as sewage backing up during heavy water use. Baffle work is covered on the septic tank repair cost page.
• An overloaded drain field. EPA says a drainfield that gets too much liquid can flood, and sewage can come up into toilets and sinks.
• A dead pump. On systems with a pump tank, a failed pump lets effluent rise until the alarm sounds; see what a septic alarm means.

Penn State Extension adds a warning: by the time sewage backs up into the home, the soil absorption area is usually already clogged, and pumping the tank alone will not remove the clogging layer, called the biomat. If the backup returns soon after a pump-out, the field is the next stop; see drain field repair and replacement.

Septic backing up after rain or a flood

Heavy rain can raise groundwater and saturate the soil so it cannot absorb effluent, Angi's leach field guide says, and NC State says runoff from roofs or paving onto the drainfield can saturate the soil to the point that it can no longer absorb any more water. Washington's Department of Health adds that floodwater can enter the system, force solids into the drainfield, or create a backup on its own.

• Use less water. EPA says that is the main way to prevent backups while the water table is high, and not to use the system at all while the soil is flooded.
• Do not pump during a flood. EPA says not to pump the tank while the drainfield is flooded or saturated, because pumping can make the tank float out of the ground.
• Plug the low drains. Penn State says to plug basement drains connected to the septic system during a flood and to turn off power to pumps.
• Expect it to take time. Penn State says the drainfield may take several weeks to recede below the level of the home after a flood.

Septic tank overflowing in the yard

Standing water or damp spots over the tank or drainfield are on EPA's list of malfunction signs, and NC State adds wet or spongy ground even when it has not rained. NC State's rules for a septic overflow are short: rope or fence off any area where sewage is on the surface, do not add soil over a wet, smelly spot, and never pipe or ditch sewage to a stream, a storm sewer or a hole in the ground.

Gurgling toilets and slow drains on a septic system

A gurgling toilet on a septic system is the first sign in Angi's list of a full tank, and EPA lists gurgling in the plumbing alongside slow tubs, showers and sinks. NC State's septic sign is slow drains that are not caused by old, clogged pipes, so one gurgling toilet with every other drain running normally is worth treating as a plumbing problem first; see why a toilet gurgles and clearing a clogged toilet. Slow drains all through the house are the septic sign on EPA's list.

Sewage backup in the basement: cleanup and disinfecting

EPA says cleanup crews should wear long rubber gloves and face splash shields and that the area should not be used until it has been completely dry for at least 24 hours. After a basement backup, EPA's flood page says to check the tank's outlet for a blockage first, then disinfect.

The agencies do not agree on bleach strength, so here is each one as published. Pick one source and follow it.

As published by each agency. The ratios differ; none of them is an average of the others.

• Carpet: Washington's Department of Health says saturated wall-to-wall carpet and pad usually cannot be adequately cleaned.
• Furniture: Mass.gov says to discard upholstered furniture and mattresses that sewage reached, and to assume anything sewage touched is contaminated.
• For a basement that took on more than a little water, see basement flooding and water damage restoration. Crews that do the cleanup itself are on the sewage cleanup page.

Sewage backup cleanup cost and insurance

A minor sewer backup repair and cleanup costs $500 to $2,000 on average in HomeGuide's sewer backup guide, and a major repair and restoration $2,000 to $15,000 or more. HomeGuide's sewage cleanup guide prices the work at $7 to $15 or more per square foot, with a small cleanup around $2,000 and a larger one up to $15,000, more in a basement or crawl space.

• Mold: HomeGuide says mold can develop within 24 to 48 hours and adds $15 to $30 per square foot to remove. See mold remediation.
• Insurance: call your insurer before cleanup starts, photograph everything first, and never sign over the claim to a cleanup company. HomeGuide says most standard homeowners policies exclude sewage backup damage, so ask whether yours has a backup endorsement rather than assuming it does.

What the septic company does on a backup call

The pumper should empty the tank through the two large central manholes, Penn State says, not the small inspection ports, and should break up the scum and mix the sludge so it all comes out; pumping through the baffle ports can damage the baffles. Ask for the outlet filter to be checked too, since Purdue ties backups to a clogged one. If the tank is fine and the backup keeps coming, the next steps are a look at the field or, on an older system, a full septic inspection before you spend on repairs. A system that has failed outright is priced on the septic replacement page.

Questions to ask before you book

• Can you pump today, and what is the price for my tank size? HomeGuide's pumping guide says $300 to $700, or $0.30 to $0.70 per gallon.
• Is disposal included, and do you charge to find and dig up the lids?
• Will you check the outlet filter and baffles while the tank is open?
• If the field is the problem, what happens next? Ask for the finding in writing.
• License and insurance. Ask for the license number where your state licenses septic work, and for proof of insurance.

Do this now while you wait for the septic company

1. Stop the water. No laundry, dishwasher, showers or flushing; NC State says to conserve water until the repair is made.
2. Close off the area. Shut the basement door, keep children and pets out (CDC), and rope off any sewage in the yard (NC State).
3. Photograph first, then call your insurer. Do not sign any form that hands the claim to a contractor.
4. If it is flooding outside, do not have the tank pumped until the ground drains (EPA), and plug the basement drains if you can (Penn State).
5. Gear up for any contact: rubber boots, rubber gloves and goggles (CDC). Wash with soap and water when done.
6. Call the septic line and say what came up, where, and when the tank was last pumped.

More septic help: septic alarm going off, septic pump replacement and pumping prices. Calls go to an independent company that serves your area and takes this kind of job; hours vary. How calls work.