7 Warning Signs Your Septic System Is Failing

Published on February 28, 2026 | Updated February 28, 2026 | By Holly Septic Services

Your septic system works quietly in the background, but when something goes wrong, you'll definitely know it. A failing septic system can be expensive and unpleasant to deal with, but catching problems early can save you thousands. Here are seven warning signs that your septic system needs professional attention.

1. Slow Drains Throughout Your Home

Slow Drains

Low to Medium Urgency

If water drains slowly from your sinks, showers, and toilets, it could indicate a problem with your septic system. Slow drains in a single fixture are usually a minor plumbing issue, but slow drains throughout the entire home suggest something is wrong with the system itself.

What This Means

Your septic tank might be full, or the drain field could be clogged or saturated with solids. When the system can't handle the volume of water coming from your home, everything backs up.

What Might Be Happening

What You Should Do

  • Don't wait—call for professional inspection
  • Have your tank pumped if it hasn't been within the last 3–5 years
  • Avoid flushing anything other than human waste and toilet paper
  • Spread out water usage while investigating

2. Sewage Odors Around the Tank or Drain Field

Foul Sewage Odors

High Urgency

If you notice strong, unpleasant sewage smells near your tank, drain field, or even inside your home, your system is likely failing. This is one of the most obvious and unmistakable signs of a problem.

What This Means

Septic systems should be completely sealed. Sewage odors indicate that waste is leaking or surfacing somewhere it shouldn't be. This is not only unpleasant—it's a public health and environmental hazard.

What Might Be Happening

What You Should Do

  • Call Holly Septic Services immediately
  • Avoid the affected area and keep children and pets away
  • Limit water usage until the system is inspected
  • Don't delay—sewage exposure is a health hazard

3. Standing Water Over the Drain Field

Wet Spots or Standing Water

High Urgency

After rain or during wet weather, if you notice standing water, pooling, or unusually soggy ground over or near your drain field, this is a critical sign of system failure.

What This Means

The drain field should absorb wastewater into the soil. If water is collecting on the surface, the soil is too saturated or the drain field isn't working. This allows untreated sewage to contaminate groundwater and surface water.

What Might Be Happening

What You Should Do

  • Call for emergency inspection and repair
  • Mark the area and keep people and pets away
  • Don't drive or park on the drain field
  • Prepare for possible drain field replacement (expensive repair)

4. Unusually Green, Lush Grass Over the Drain Field

Bright Green Grass Patch

Medium Urgency

While it might seem nice to have a greener lawn, an unnaturally bright green or lush patch of grass directly over or near your drain field is actually a warning sign. The grass may also be growing faster or taller than the surrounding lawn.

What This Means

Septic effluent (treated wastewater) contains nutrients that make excellent fertilizer. If grass is thriving excessively in one spot, it suggests treated wastewater is being released into that area—possibly because the drain field is failing and backing up.

What Might Be Happening

What You Should Do

  • Schedule a professional inspection soon
  • Avoid mowing or disturbing the area
  • Reduce water usage in your home
  • Don't plant trees or structures over this area

5. Sewage Backup Inside Your Home

Indoor Sewage Backup

High Urgency

If sewage backs up into your toilets, showers, sinks, or other plumbing fixtures inside your home, your septic system is failing. This is one of the most serious and health-threatening warning signs.

What This Means

Sewage is being forced back into your home because the system can't handle the volume of wastewater. This is unsanitary and dangerous, exposing your family to harmful bacteria and pathogens.

What Might Be Happening

What You Should Do

  • Stop using all water immediately (toilets, showers, sinks, laundry)
  • Call Holly Septic Services for emergency service
  • If available, use a portable toilet temporarily
  • Prepare for emergency pumping or repair

6. Gurgling or Unusual Sounds in Your Plumbing

Gurgling Pipes and Toilets

Low to Medium Urgency

If you hear gurgling sounds coming from your pipes, drains, or toilets—especially when you're using water in another part of the home—it's a sign of air in the plumbing system. This usually indicates a blockage or backup.

What This Means

As wastewater tries to drain but encounters resistance, air gets trapped in the pipes, creating gurgling or bubbling sounds. This often precedes more serious backup issues.

What Might Be Happening

What You Should Do

  • Schedule an inspection within a few days
  • Have your tank pumped if overdue
  • Avoid excessive water use until inspected
  • Monitor for worsening of symptoms

7. High Nitrate Levels in Well Water

Contaminated Well Water

High Urgency

If you have a private well and water testing shows elevated nitrate levels, your septic system may be contaminating your groundwater. Nitrates in well water are a direct indicator of septic system failure.

What This Means

Septic systems treat wastewater, but failing systems can leak untreated waste into groundwater. High nitrates indicate that your well may be drawing water contaminated by your septic system—or your neighbor's system.

What Might Be Happening

What You Should Do

  • Have a septic professional inspect your system immediately
  • Test your well water regularly (at least annually)
  • Consider alternative water sources if contamination is confirmed
  • Consult with Oakland County Health Department
  • Be prepared for system repairs or replacement

What To Do If You Notice These Signs

Action Steps

If you notice one or more of these warning signs, don't panic—but do act quickly. Here's what you should do:

Prevention Is Cheaper Than Repair

The best way to avoid a failing septic system is to maintain it properly:

Regular maintenance costs a few hundred dollars every few years. System replacement can cost $5,000 to $20,000 or more. It's clear which option is better!

Don't Wait—Get Professional Help Today

If you've noticed any of these warning signs in Holly, Michigan, don't ignore them. Holly Septic Services has helped countless homeowners diagnose and fix septic problems before they become catastrophic. We offer professional inspections, emergency service, and expert repairs.

Noticed a Problem? Call Now

Get professional septic system inspection and repair in Holly, Michigan

(248) 805-1889