March 17, 2025 ☼ Septic System ☼ Wastewater ☼ Alternative Treatment System

A few years ago, I encountered a non-traditional septic system in Passaic County, New Jersey. The system was installed in a high-groundwater area—a stream ran along the property line—and the backyard was small. It was a mounded septic system with:

• One settling tank
• A pump dosing tank
• A small pressure leach field

A Unique Addition: The Pirana System

What made this setup unique was the installation of a Pirana System, a submerged attached growth bioreactor (SAGB). This aerobic septic system modification turned what would have been a traditional anaerobic system (without oxygen) into an oxygenated system.

The Pirana bioreactor does two things:

• Oxygenates the black water effluent
• Introduces a specialized bacterial plug, creating a bacterial ecosystem that breaks down sludge

Initially, I was skeptical because the system wasn’t working properly.

Signs of a Failing Leach Field

The leach field (sometimes called a drain field) wasn’t draining correctly. The soil above it felt squishy—a red flag for septic failure. After inspecting the system, I found a thick bio-mat blocking the effluent’s proper absorption into the soil. In other words, the leach field was on the verge of failure. It hadn’t completely failed yet, but it was in critical condition.

What Went Wrong?

After reviewing the manufacturer’s website and speaking with the inventor, I determined that:

• The blower (air diffuser) had failed
• The bacterial colony inside the bioreactor had died

According to the manufacturer, if I replaced the air diffuser and reintroduced the bacterial colony, the system should start functioning again.

Did I mention I was skeptical?

How Does the Pirana System Work?

A typical Pirana System consists of three components:

• The bioreactor — Installed in the septic holding tank near the inlet
• An air diffuser — A 40-watt pump that aerates the system
• A bacterial plug — Contains specialized bacteria to break down waste

Installation Overview

1. The bioreactor is placed inside the septic tank.
2. A ½-inch PVC pipe is run from the bioreactor up through the riser.
3. This pipe connects to a 40-watt air diffuser inside the house.
4. The air diffuser continuously blows oxygen into the bioreactor, allowing the bacteria to thrive.

Here’s a helpful video demonstration from the manufacturer:

My Results: Does the Pirana System Work?

Despite my skepticism, I decided to try replacing the air diffuser ($350) and adding a new bacterial plug ($100 for two). Here’s what the holding tank looked like before I restarted the blower:

The water was black, and sludge had built up on the surface. The system was in critical condition, and I could see why the leach field was failing.

After just six days, I noticed significant changes:

The sludge layer was breaking up and the water color had changed from black to gray.

3 Weeks Later the the leach field was recovering!

• No more “squishy” ground
• No standing effluent in the inspection ports

Final Verdict: Does the Pirana System Work?

Yes, the Pirana System worked—but with some important caveats.

When It Works Best:

• At the first signs of trouble (foul odors, squishy soil, or standing water)
• If the septic system hasn’t fully failed yet

When It’s Too Late:

• If wastewater is backing up into your house
• If the septic system has already collapsed

Cost Comparison:

• My Pirana System Fix: ~$450 (air diffuser + bacterial plug)
• New Pirana System Installed: ~$2,500-$4,500 (bioreactor + air diffuser + bacterial plug + labor and parts)
• New Septic System: $20,000–$40,000

Final Recommendation

If you catch the problem early, a Pirana System upgrade could save you thousands of dollars and extend the life of your septic system. But if your septic system is already failing, it may be too late to save it.

If you need help, don’t hestiate to Call Me at 973-750-8877.