Conventional System
Conventional System
- Typically includes a septic tank and a gravity-fed drain field
- Waste is broken down by anaerobic bacteria
- Effluent is dispersed into the soil through perforated pipes
- Requires minimal mechanical parts
Maintenance Tip: Pumping is recommended every 3–5 years to avoid solids building up and damaging the drain field.
Aerobic Treatment Unit (ATU) System
Aerobic Treatment Unit (ATU) System
- Uses oxygen to promote bacterial breakdown of waste
- Typically includes multiple tanks and an air compressor or pump system
- Final treated water is disinfected (usually with chlorine) and then sprayed onto the lawn or dispersed
- Requires more frequent maintenance, inspections, and chlorine replacement
Common in areas with shallow soil or limited space for drain fields.
Septic System Diagrams
Measuring Scum and Sludge Layers in Septic Tanks – Texas Standards
In Texas, the Texas Commission on Environmental Quality (TCEQ) recommends regular monitoring of the scum and sludge layers in septic tanks to determine when pumping is needed and to ensure proper system operation.
Scum (floating solids) and sludge (settled solids) should be measured to prevent solids from entering the drain field and causing system failure.
How Scum & Sludge Are Measured
Certified inspectors or pumpers typically use a "sludge judge" or clear measuring rod with marked measurements. Here's how it works:
1. Scum Layer Measurement (Top Layer)
- A slotted or hooked rod is gently inserted through the scum layer.
- Resistance is felt when the rod hits the bottom of the scum layer.
- The depth of the scum is noted and distance from the outlet baffle is measured.
2. Sludge Layer Measurement (Bottom Layer)
- A transparent sludge sampler is slowly lowered to the tank bottom.
- Once fully submerged, it's sealed and removed to view sludge depth.
- Measurements show how much of the tank is occupied by sludge.
When to Recommend Pumping (Per TCEQ Guidelines)
- If sludge and scum combined occupy 1/3 or more of the total tank volume
- If sludge layer is within 12 inches of the outlet
- If scum layer is within 3 inches of the outlet
- If any part of the tank is backing up or if effluent is reaching the drain field with solids present
How a Septic System Works – Understanding the Basics
A septic system is an underground wastewater treatment solution commonly used in homes not connected to a municipal sewer. It is designed to receive, treat, and dispose of wastewater and solids from a building’s plumbing system.
Key Components of a Septic System:
- Septic Tank
- The first stop for wastewater
- Solids settle to the bottom and become sludge
- Fats, oils, and grease float to the top, forming scum
- The middle layer of relatively clear effluent flows out of the tank
- Drainfield (Leach Field)
- Effluent exits the septic tank and enters a network of perforated pipes
- Water is gradually released into the soil, where naturally occurring bacteria further filter contaminants before reentering the groundwater system
Why Maintenance Matters
Over time, scum and sludge build up and can overflow into the drainfield if not pumped out. This can lead to:
- Clogged or failed drainfields
- Sewage backups into the home
- Contamination of soil and groundwater
- Costly system repairs or replacement
Scum and sludge should never reach the drainfield. Regular septic pumping—usually every 3 to 5 years depending on system size and usage—is essential to keeping your system functioning properly.
Trust Priority Inspection Services
At Priority Inspection Services, we offer licensed septic system inspections that include:
- Visual checks of accessible components
- Drainfield observations
- Maintenance recommendations
- Guidance on scum/sludge layer testing and pumping needs
TCEQ License #: OS-003530