Signs your septic system is failing in Michigan, and what to do first

What EGLE counts as a failed system

A system does not have to flood the basement to count as failed. EGLE defines failure as any of these: sewage backing up into the building, sewage discharging to the ground surface, contamination of surface water or drinking water, any part of the system being bypassed, the system being an illicit discharge, no absorption system at all, or a tank that has failed structurally. That definition matters because the loan program asks the local health department to document a failing or near-failing system.

The signs, indoors and out

EGLE’s list of warning signs runs from the quiet to the obvious. Inside the house: slow drains, gurgling, and sewage backing up. Outside: wet spots, bright green and lush grass over the tank or the drain field, sewage odors, pipes visibly discharging, and algal blooms in nearby water. Any one is reason to act. Several together are a strong signal.

What you see	What EGLE or EPA says about it	Who to call first
Slow drains or gurgling in several fixtures	EGLE lists both as signs; EPA says solids that leave the tank clog the drain field	A septic company, or your county health department
Sewage backing into a drain, toilet or basement	Failure by EGLE’s own definition	Your county health department
Wet ground or bright green grass over the tank or field	EGLE lists both; EPA says an old, clogged field can pond or surface sewage	An inspection, and the health department if sewage is surfacing
Sewage odor	EGLE lists it; EPA adds that a vent pipe can freeze in a prolonged cold spell and cause odors	An inspection
Pipes discharging, algal blooms nearby	EGLE lists both; contaminating surface or drinking water counts as failure	Your county health department

The failure signs tool walks through the same list with a few questions and tells you to call first or to book a visit.

Why drain fields fail

EPA says most systems malfunction because of poor design or poor maintenance, and that solids migrating from the tank clog the drain field. The fix is pumping before the solids escape, which is why the pumping interval guide matters. Age is another cause: EPA says a drain field more than 25 to 30 years old can develop a thickened biomat that causes ponding, surfacing or backup, and that owners should plan an upgrade. EGLE gives a conventional system 25 to 40 years and says the pumps, alarms and panels wear out sooner.

Michigan adds roots. EGLE calls root infiltration one of the leading causes of system failure in the state, and says to keep trees and large shrubs away from the system and to avoid walnut, maple, cottonwood, aspen and willow near it. It also says not to park or drive on any part of the system, not to put dumpsters or heavy machinery on it, and to direct gutter downspouts away. A drain field that is clogged may need to be replaced entirely, and significant root intrusion may force major repair or replacement. See the drain field page for county setbacks.

What to do in the first hour

EGLE says to contact your local health department for guidance and not to try to service a septic system yourself, because of disease, dangerous gases and electric shock. EPA’s advice for a backup into the house is to avoid contact, keep the area unused until it has been completely dry for at least 24 hours, and disinfect with a solution of 90 percent water and 10 percent household bleach. Stop running water so you do not add to the problem. If the yard or tank is flooded, do not call for pumping yet: EGLE says to wait until surface water and groundwater recede, because pumping into high groundwater can float a concrete tank or crush a plastic one.

Check the water coming in before you blame the soil

EGLE’s yearly checklist asks owners to look for leaking fixtures, and its guidance is to keep sump pumps, water softener discharges and downspouts away from the septic system. EGLE also says residential septic systems in Michigan are not designed for softener backwash and that most local sanitary codes prohibit connecting such discharges. If a softener line, a sump pump or a downspout reaches your tank or field, tell the inspector at the start. It can explain a field that is soggy in wet weather or after a heavy laundry day, and it may change what the repair looks like.

Cold weather and odors

In a prolonged cold spell a vent pipe can freeze and cause odors indoors or out, EPA notes. A smell in a hard freeze is therefore not proof of a failed drain field, and an inspector can separate the two causes. Spring brings the opposite risk: snowmelt and rain raise the groundwater, which EGLE says is the reason not to pump a flooded tank until the water drops. The winter and spring care guide covers the season.

How common failure is in Michigan

Local health departments reported 4,332 failed residential systems for 2023, out of a state where EGLE says more than 1.3 million septic systems treat household wastewater. The report is missing data for 17 of the 83 counties, so that count understates the departments’ caseload. It counts failures they evaluated, not every failing system. EGLE’s news release says “by some estimates” more than 20 percent of Michigan systems are failing. We cite that as an estimate made by others.

Where to get help

County health departments are the first call. St. Clair County, for example, runs a 24-hour anonymous line to report a failing system. For repair money, EGLE and Michigan Saves lend up to $50,000 for failing or near-failing systems, but the failure has to be documented by the local health department, so the first call also starts the paperwork. The loan guide has the rules, and the septic repair page has county permit fees.