Entitlement guide
Septic (OSSF): when the land has to treat the wastewater.
Without sewer, the septic field becomes part of the site plan. It takes land, it depends on soil, and it can set what you are allowed to build.
The short answer
An on-site sewage facility, or OSSF, treats wastewater on the property. Texas rules come from the Texas Commission on Environmental Quality. Most counties, and some cities and river authorities, run the local program as the authorized agent, so they review and permit the system.
The design depends on the soil, the slope, the water table and how much wastewater the use produces. The field and its replacement area need room, and they have to stay clear of wells, water lines, easements and floodplain. On many rural commercial sites, the septic field decides where the building goes.
- Whether the site has a sewer provider, or septic is the path
- Who the authorized agent is, and whether the court approves commercial systems
- Mapped soils and slope, as a screen before test pits
- Aquifer zone limits on density and system type
- Room for the field and replacement area after setbacks and easements
- Whether the expected flow stays within the county program
Why it can stop a deal
Where projects get caught.
The soil will not take it
Shallow rock, heavy clay or a high water table can rule out a standard field and push you to an engineered system that costs more and needs maintenance.
The field does not fit
Once setbacks, drives, parking, detention and a fire tank are placed, the field and its replacement area may not fit. Something has to give.
The use produces too much
High-flow uses can exceed what a county septic permit covers, which moves the project to a state wastewater permit with a much longer path.
How it works
How it usually works in Central Texas.
Rules differ by city, county and utility, and they change. Treat this as orientation and confirm with the approving authority.
Who reviews it. In most Central Texas counties, the county development or environmental office is the authorized agent for OSSFs in unincorporated areas. Some cities run their own programs. Near some lakes, a river authority may hold that role. Some counties send non-residential systems to commissioners court for approval, which puts a court agenda date on your schedule.
The site evaluation. A licensed site evaluator or professional engineer digs soil test pits and records the soil profile. That evaluation, plus the expected daily flow, drives the system type: a conventional drainfield, a low-pressure dosing system, drip irrigation or an aerobic treatment unit with spray. Engineered systems usually need an ongoing maintenance contract.
Lot size and density. State rules set minimum lot sizes for subdivisions on septic, depending on whether water comes from a public system or private wells. Edwards Aquifer zones add their own limits. On the recharge zone in particular, residential density and system types can be restricted. Check the aquifer guide if your site is in one of those zones.
Legal lot first. Counties generally will not permit an OSSF on a tract that is not a legal lot. That makes platting a prerequisite, which is why VALITER puts legal footing ahead of septic in the order of checks.
Large flows. Systems above the county program's size limit go to the state for a different kind of permit. If your use could produce a lot of wastewater, find out early which side of that line you are on.
Who decides
The people and offices involved.
| Who | What they decide |
|---|---|
| County or city authorized agent | OSSF permits, inspections, local rules |
| Commissioners court | Approval of some non-residential systems, depending on county |
| TCEQ | State rules, and permits for systems too large for the local program |
| Site evaluator or engineer | Soil evaluation and system design (a professional gate) |
- Who is the authorized agent for OSSFs at this address?
- Does a commercial system here go to commissioners court?
- What do the soils look like, and is a test pit visit scheduled?
- Does the field and its replacement area fit after everything else is placed?
- Is the site in an aquifer zone that limits system type or density?
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