What Types of Septic Systems Are Used in Texas?
Texas uses standard conventional septic systems where the soil allows them. Where it does not, the lot gets an aerobic or other non-standard system. A site evaluation of the soil decides which one.
Around Leander, most new systems are spray or drip. TCEQ’s 2025 report covers Williamson County, unincorporated Travis County and the LCRA’s Travis County zones. More than three of every four new systems there were one of the two.
What are the main types of septic systems in Texas?
TCEQ’s rules sort system designs into three classes: standard, proprietary and non-standard. The class sets who may build it. An Installer I may build most standard systems, plus the proprietary chamber and gravelless pipe fields. Aerobic, spray, drip, low-pressure dosing and mound systems take an Installer II.
Bravo Septic installs standard systems. Our septic system installation page covers that work.
| System type | How it treats and disperses the water | TCEQ class | Who may build it | Upkeep it needs |
|---|---|---|---|---|
| Conventional | Solids settle in the tank; the liquid runs by gravity into gravel trenches and the soil treats it | Standard | Installer I or II | Pump the tank every three to five years |
| Leaching chamber or gravelless pipe | The same tank; plastic chambers or wrapped pipe take the place of gravel | Proprietary | Installer I or II | Same as conventional |
| Pumped drainfield | A pump tank doses the liquid into the field | Standard | Installer I or II | Pumping, plus a working pump and high-water alarm |
| Unlined ET bed | Water leaves through evaporation and the plants on top | Standard | Installer I or II | Tank pumping |
| Low-pressure dosing | A pump pushes the liquid under low pressure through perforated pipe | Non-standard | Installer II | Pump and alarm upkeep |
| Mound | A drainfield built above the native soil, dosed by a pump | Non-standard | Installer II | Pump and alarm upkeep |
| Aerobic with spray | Air feeds bacteria that clean the water; it is disinfected and sprayed on the lawn | Proprietary | Installer II | Maintenance contract, tests and reports; pumping by sludge depth |
| Aerobic with drip | Aerobic treatment, then a filter and drip lines buried in the topsoil | Proprietary | Installer II | Maintenance contract and reports; pumping by sludge depth |
TCEQ’s table lists aerobic units as proprietary. In practice they sit with the non-standard systems. A professional engineer or registered sanitarian designs them, and an Installer II builds them. The table leaves out prices. For those, see what each system costs to install in Texas.
How does a conventional septic system work?
A conventional system has two parts: a septic tank and a drainfield. In the tank, heavy solids settle to the bottom and grease floats to the top. The liquid in between flows out to the field.
The field is a set of shallow trenches with perforated pipe in gravel. Microbes in the soil below do the final treatment. Water moves by gravity, so the system needs no power.
TCEQ’s rules allow a standard drainfield only where every soil and site factor checks out. The trench needs two feet of suitable soil beneath it before rock, clay subsoil or groundwater.
Three related designs are also open to an Installer I:
- Leaching chambers and gravelless pipe take the place of gravel. The EPA says chambers are easier to deliver and build.
- A pumped drainfield adds a pump tank that doses the field. The rules allow it only for single-family homes on slopes of 2 percent or less.
- An unlined ET bed returns water to the air through evaporation and plants. The rules allow ET systems only where average yearly evaporation is greater than rainfall.
How does an aerobic septic system work?
An aerobic system treats the water more before it reaches the ground. The EPA compares it to a small sewage plant. An aerator pushes air into the treatment tank, and the oxygen feeds bacteria that clean the water further. Some units add a pretreatment tank and a final tank with disinfection.
The treated water can then go to one of two kinds of field:
- Spray: the water is disinfected, then sprayed on the lawn through low-angle sprinkler heads. The spray area cannot be a food garden. Spray areas less than 20 feet from a property line need a timer set for midnight to 5:00 a.m.
- Drip: a filter and small pressurized lines, buried at least six inches deep, spread the water under the topsoil. TCEQ’s rules allow drip with secondary treatment in every soil class, clay included.
Two other non-standard designs pump the liquid from a septic tank. Low-pressure dosing pushes the liquid under low pressure through perforated pipe. A mound is a drainfield built above the native soil. The EPA lists mounds for shallow soil, high groundwater or shallow bedrock.
Why do so many lots around Leander need a non-standard system?
The soil decides, and a site evaluation reads it. TCEQ’s rules set a system’s type and size from the soil and site findings. A licensed site evaluator or professional engineer does that work.
Much of the ground west of I-35 is shallow rock. Much of the ground east of it is heavy clay. Texas A&M AgriLife Extension says only nonstandard drain fields can be used in clay. Williamson County’s OSSF guide says a standard absorption system is only allowed in suitable soil conditions.
Aerobic systems work around poor ground. The EPA says they fit smaller lots, inadequate soil and high water tables.
What went in around Leander in 2025?
TCEQ’s 2025 report counts new systems by type for each permitting office:
- Williamson County: 490 new systems. Spray led with 241 and drip followed with 139. Only 17 were standard trench or bed systems.
- Travis County’s program (unincorporated county): 144 new systems, led by 89 drip and 24 spray. One was a standard trench or bed.
- The LCRA’s Travis County lake zones: 124 new systems, with 78 drip and 18 spray. One was standard.
- Texas as a whole: 41,990 new systems. Spray led with 24,392, about 58 percent. Standard trench or bed systems numbered 3,105.
Across the three local offices, 19 of 758 new systems were standard trench or bed systems. That is about 1 in 40.
What upkeep does each type of septic system need?
Every septic tank needs pumping. TCEQ recommends pumping a conventional tank every three to five years. For an aerobic unit, it depends on the sludge depth and the maker’s guidance. We pump conventional and aerobic tanks; see septic tank pumping.
Aerobic, spray and drip systems need more. State rules require a maintenance contract for them, and a licensed maintenance provider handles that work. The provider reports to the permitting authority at least every four months, or every six months with an electronic monitor.
Two years after an aerobic unit goes in, homeowners may do the maintenance themselves. Some permitting authorities are stricter, so ask yours first. If your system uses chlorine tablets, TCEQ says never to use swimming pool tablets.
Low-pressure dosing and mounds fed by a plain septic tank need no maintenance contract under the state table. Their pump and high-water alarm still have to work.
On a conventional system, a septic inspection measures the sludge so you know when pumping is due. A soggy or smelly conventional field is its own problem, covered on our drain field repair page.
Which septic system fits your lot?
The site evaluation answers that, and the office that covers your address issues the permit. Our guide to the septic permit process in Texas walks through the steps.
Some evaluations call for an aerobic or other non-standard system. That install takes an installer licensed for non-standard systems (a TCEQ Installer II). We tell you what your site evaluation means before you spend money. When a standard design fits the lot, we install it.
Bravo Septic is a TCEQ-licensed OSSF installer, and you get a quote before any work begins. Call (512) 887-4458, or read about our conventional septic installs.