Aerobic septic problems & case studies

A technical resource covering the most common — and several uncommon — failures we see in aerobic treatment systems across Brazoria County. We document these issues so homeowners recognize symptoms early, before a minor problem becomes a major expense.

System pumping tips

Minimize pump-out frequency

Frequently asked questions

Quick answers by topic

Common problems

Many failures can be prevented through basic maintenance and regular inspection. Catching these early extends the life of your aerobic treatment unit.

Air pressure

During inspection visits, we measure air system performance. Pressure that's too high or too low creates cascading problems depending on severity.

High air pressure

  • • More frequent pump-outs
  • • High solids build-up in pump tank
  • • Premature air pump failure

Normal air pressure

  • • Less frequent pump-outs
  • • Efficient bacterial breakdown of solids
  • • Extended air pump lifespan

No air pressure

  • • Bad odor
  • • Untreated wastewater sprayed onto lawn
  • • Constant alarm state on controller

Caused by broken pipe, damaged diaphragms, clogged intake filter

Very little air entering the effluent inside an aerobic treatment unit
High air pressure: almost no bubbles entering treatment tank
Much more air entering the effluent inside the ATU
Normal pressure after cleaning air stones: healthy bubble count

Wire connections

Some installers and manufacturers make wiring connections for the water pump inside the pump tank. The water in the pump tank produces hydrogen sulfide gas and chlorine gas from the chlorine treatment. Both compounds are highly corrosive.

Result: Corroded wires cause shorts in the water pump and potentially the controller.

High solids: time to pump

Your treatment unit has multiple compartments. We check levels in each one during inspection visits to prevent issues before they arise.

Side-effects of high solids

  • • Premature water pump failure
  • • Solids spraying onto lawn
  • • Clogged filters, backed-up system
Need more info? Check our section on septic pumping
High solid level in aerobic treatment system
Excessive solids accumulation in treatment compartment

Inaccessible openings

Septic tank openings are buried
Buried tank access prevents proper inspection

Buried or otherwise inaccessible tank openings prevent us from fully inspecting your system. We're unable to determine if the septic system needs pumping, has aeration problems, or has a working aerobic chamber.

Additional costs

When you have your aerobic treatment tank vacuumed out, most pumping companies charge extra to dig these openings up — or worse, skip them entirely, leaving only part of your tank clean.

Root infiltration

When a tree grows nearby an aerobic septic system, its roots will find their way inside. Even if the tree is over 15 feet away from your main tank, roots branch out and expand, causing damage to pipes, conduit, or even your tank.

Roots have infiltrated this pump tank
Tree roots infiltrating pump tank interior
Root barrier stops grass roots from entering the septic tank
Root barrier installation preventing grass root entry

Prevention strategy

The best approach is to keep trees and large shrubbery away from your septic system. In certain situations we'll install a root barrier, preventing smaller roots from entering your tank. (Tanks installed at ground level can be infiltrated by grass roots, even though they're tiny.)

Uncommon problems: case studies

Other types of aerobic septic problems can be caused by factors outside of routine control. These issues can smolder for years before manifesting. Well-documented case studies below.

Case study #1: Missing trash tank

Background

Before a manufacturer of an aerobic wastewater treatment system can sell a particular model in Texas, it is sent to a testing facility for a rigorous six-month operational test.

These six-month tests cost a manufacturer $250,000 for each different model tested. After receiving the TCEQ seal of approval, that system must be installed as tested by the facility. For obvious reasons, there can be no changes to the installation procedures and equipment.

This case study is about a TCEQ-approved two-tank aerobic wastewater treatment system (trash/pre-treatment + ATU) installed without the trash/pretreatment tank (ATU only).

Situation

Twenty years ago, the environmental health department of a county on the gulf coast arbitrarily changed the design parameters of a TCEQ approved wastewater system. Years later, Advanced Aerobic Systems became the maintenance provider for new clients who all had the same complaint: during heavy rain/storm events, or high tides (neap tides) their aerobic wastewater system would back up into their elevated beach homes.

Observations

These county-permitted wastewater systems were installed without the TCEQ-mandated trash tank. Sewer effluent from the elevated home flowed directly into the treatment compartment. There was no pre-treatment (settling out of solids) as you would normally have with a trash tank.

The solids are now circulating in the treatment compartment. Compounding the problem, the tank design has an opening directly over the common wall that separates the treatment and clarifier compartments.

When the disposal field became waterlogged during a heavy rain event or high tide, everything backed up into the home. The elevated water level in the tank allowed the solids from the treatment tank to flow over the common wall into the clarifier. As the water table lowered, solids from the clarifier would then flow into the 8" gravelless pipe in the disposal field. Eventually the disposal field will fill with solids.

Solution

Always install according to tested specs. A separate trash tank needs to be added to these systems. Don't cut corners.

Case study #2: Cracked tank

Background

Before a manufacturer of a particular OSSF can sell their model in Texas, it is sent to a testing facility for a rigorous six-month regimen. If the tank cracks during the test it will fail outright. These tests cost the manufacturer $250,000 for each tank. This case study is about an OSSF that had numerous cracked walls.

Situation

Advanced Aerobic Systems became the maintenance provider for an installed OSSF located adjacent to a river. The owner wanted a maintenance contract in place before selling his 4 bedroom home. The tank was three years old.

Cracked aerobic septic tank wall
Multiple cracks in common interior tank wall
Observations

Our inspection of the one tank, 4 compartment OSSF revealed low water in all 4 compartments. Upon further inspection Advanced Aerobic Systems found large cracks in the common interior tank wall that the pump tank has with three other compartments (trash, treatment and clarifier). In addition, the pump tank exterior wall was cracked, allowing effluent to escape into the ground.

The effluent in the trash, treatment, and clarifier compartments leaked into the pump tank compartment due to multiple cracks in the common wall separating them. This caused the water level in all tanks to equalize, and ultimately led to untreated effluent with harmful pathogens being pumped out onto the ground.

A detailed inspection was completed and provided to the owner, along with multiple pictures of the tank. We also informed the county of the situation, providing them with our recommendation to replace the cracked tank.

Sand pouring into cracked aerobic septic tank
Outer wall crack with sand infiltration from outside
Action

The owner wanted a second opinion from the original installer. That installer said "don't worry about it because the cracks will eventually seal themselves with silt and the tank will work ok." The county inspector visited the site and because they didn't find "solid waste overflowing" from the system they closed the case. The county indicated that either the owner or installer had to prove that coliform bacteria (pathogen indicator) was being pumped to the spray field. This required taking a water sample to the lab. However, this procedure is not required in this county and therefore was not included on the maintenance contract. On the prima facia evidence of cracked walls and uniform low water levels, other counties would require either the tank be satisfactorily repaired or replaced.

Solution

Ultimately the county did not take further action. The owner sold the house to someone new, who now has no idea their tank is pumping untreated pathogens onto the ground.

Experiencing any of these problems?

We diagnose the root cause, explain what we find, and give you a written estimate before starting any work. Licensed, experienced, and available when you need us.

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