Warning signs
A septic system fails underground first. EPA publishes a short list of what you can see and smell. If those signs are present, call a licensed professional — not a chemical additive.
EPA’s common signs of a failing system
From Frequent Questions on Septic Systems and Resolving Septic System Malfunctions (both last updated 11 March 2026):
- Water and sewage from toilets, drains, and sinks backing up into the home’s plumbing
- Bathtubs, showers, and sinks draining very slowly
- Gurgling sounds in the plumbing system
- Standing water or damp spots near or over the septic tank or drainfield
- Sewage odors around the septic tank or drainfield
- Bright green, spongy lush grass over the septic tank or drainfield, even during dry weather
- Straight pipe discharging untreated wastewater to the ground surface
- Algae blooms in nearby lakes or waterbodies
- High levels of nitrates or coliform bacteria in surface waters or drinking water wells
If sewage is in the house
EPA (malfunctions page): avoid contact; sewage may contain harmful pathogens. Contact the local health department. Cleanup personnel should wear protective clothing. After cleanup, EPA describes disinfecting exposed items with a mixture of 90 percent water and 10 percent household bleach, then drying the area thoroughly and not using it until it has been completely dry for at least 24 hours. That is EPA’s language, not a substitute for local public-health direction during a backup.
Odors are not always a failed tank
EPA: a smell may come from a roof vent. Vents clog with leaves or freeze. Soft, wet, or spongy soil around the drainfield with no recent heavy rain is a stronger sign of failure. EPA: it is not possible to diagnose the exact cause of an odor remotely — contact a local septic service provider and/or plumber.
When to call a licensed pumper
- You are due for routine pumping (EPA: typically every 3 to 5 years; see how often).
- A professional has measured sludge and scum past EPA’s cutoffs (scum within 6 inches of the outlet bottom, sludge within 12 inches of the outlet, or sludge and scum more than 25 percent of liquid depth).
- Toilets or drains are backing up and a plumber has not found a simple indoor clog.
Call the local health department as well when wastewater is surfacing in the yard, a straight pipe is discharging, or a private well has tested high for nitrates or coliform. EPA: surfacing untreated wastewater is a direct public health hazard.
Do not pour septic-tank additives down the drain as a substitute for pumping. EPA: additives containing bacteria or chemicals are not recommended for domestic wastewater treatment. Penn State Extension: relying on additives rather than pumping may result in failure of the entire system.
Find a licensed pumper on this site
- York County, PA · Geauga County, OH · Shawano County, WI
- Montana · North Dakota · Iowa · Clallam County, WA
- Other states — official tools
Sources
- U.S. EPA, Frequent Questions on Septic Systems, last updated 11 March 2026.
- U.S. EPA, Resolving Septic System Malfunctions, last updated 11 March 2026.
- U.S. EPA, How to Care for Your Septic System, last updated 17 August 2026.
- U.S. EPA, New Homebuyer’s Guide to Septic Systems, EPA-832-F-17-010, August 2017.
- Penn State Extension, Septic Tank Pumping, updated 21 July 2023 (additives).