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Conventional Septic Systems
A conventional septic system, often called a standard system, is the most common type, especially in older construction. It is typically installed at a single-family home or small business.
Overview
Conventional systems
01How a conventional system works
Wastewater flows from the building into a septic tank, where solids settle and begin to break down. The liquid, called effluent, then flows to a drainfield: a set of shallow underground trenches or a bed filled with gravel or stone and perforated pipe. The effluent drains into the soil, where natural processes treat it further.
The gravel or stone drainfield is a design that has been used for decades and works well when the soil can absorb and treat the water.
02When a conventional system is a good fit
- Soil that drains at a suitable rate
- Enough groundwater separation and lot space for the drainfield
- Homes and small businesses with moderate, steady wastewater flow
03When another system may be better
Clay soil, a high water table or a small lot can rule out a conventional system. In those cases an aerobic treatment system with drip or spray distribution may be the right answer. Our site evaluation will tell you which applies.
Technical detail
The engineering behind it
- Components
- Two-compartment septic tank and a soil absorption field (drainfield)
- Tank
- The first compartment holds about 1/2 to 2/3 of the total tank length
- Drainfield
- Perforated pipe in gravel under geotextile fabric
- Access
- Where buried deeper than about 12 inches, risers bring access to within 6 inches of ground level
Show diagrams and process detail
Schematic, not to scale. Based on the description in Texas A&M AgriLife Extension publication L-5347.
- 1
Two-compartment septic tank
Solids settle and are digested by bacteria. A baffle wall keeps solids in the first compartment, which holds about half to two-thirds of the tank length.
- 2
Risers and lids
Risers bring access to the surface so tanks can be inspected and pumped without digging. Lids are kept at or near ground level.
- 3
Gravel drainfield
Perforated pipe sits in gravel under geotextile fabric. Effluent trickles out along the pipe and spreads across the gravel.
- 4
Soil treatment
Water moves down through the soil, where microorganisms consume contaminants. It then evaporates, is taken up by plants, or reaches groundwater.
FAQs
Conventional systems: common questions
What is a standard septic system?
A standard, or conventional, system has a septic tank and a drainfield (also called a soil absorption field). It is the most common type of septic system.
How do I maintain a conventional septic system?
Have the tank pumped on a regular schedule, protect the drainfield from vehicles and heavy loads, avoid flushing items that do not break down, and fix leaks promptly. The Texas A&M fact sheet below explains operation and maintenance in detail.
Ready to talk about your project?
Call 409-651-3045 or send us a message.