Question 1

Aerobic vs. conventional anaerobic — what decides which one my property needs?

Accepted Answer

Nothing is chosen by preference: "the type and size of an OSSF shall be determined on the basis of the soil and site information developed according to §285.30," and a standard subsurface (conventional) absorption system may be used only if all soil and site criteria are suitable — otherwise a proprietary or non-standard system such as an aerobic treatment unit must be used (30 TAC Chapter 285, §285.32). The controlling factors found in the site evaluation are soil class/texture (Class Ia gravelly sands through Class IV clays), restrictive horizons, groundwater within 24 inches of the excavation bottom, slope, floodplain, lot size, setbacks, and easements (30 TAC Chapter 285, §285.30; Northeast Texas MWD OSSF FAQs). In practice, tight clay soils, shallow seasonal water tables, rocky ground, and small lots are what push a Texas property to aerobic treatment with spray or drip dispersal…

Question 2

Do I need a permit to install a septic system in a Texas county, and who issues it?

Accepted Answer

Yes — with narrow exceptions, a permit and approved plan are required to construct, install, alter, repair, extend, or operate an on-site sewage facility (OSSF) in Texas (TCEQ, Getting a Permit for an OSSF). The rule states a person must hold a permit and an approved plan unless an exception in 30 TAC §285.3(f) applies, and that the TCEQ executive director is the permitting authority unless a local governmental entity holds an OSSF order, ordinance, or resolution approved by the executive director (30 TAC §285.3). In practice most permits are issued locally: TCEQ notes it "is not often the OSSF permitting authority," and the TCEQ regional office issues permits only where no local program has been authorized (TCEQ, Getting a Permit for an OSSF).

Question 3

How many acres do you really need for a septic system in Texas?

Accepted Answer

There is no statewide "you must own X acres" rule; the actual minimums are lot-size rules tied to how a subdivision was created — subdivisions of single-family dwellings platted or created after the rule's effective date must have lots of at least 1/2 acre if served by a public water supply and at least 1 acre if not served by a public water supply (30 TAC §285.4(a)(1), TCEQ RG-472; 30 TAC §285.4, Cornell LII). The "10-acre rule" is a permit exemption, not a minimum: no planning materials, permit, or inspection are required for a single-family dwelling on a tract of 10 acres or more only if the OSSF causes no nuisance or groundwater pollution, all parts are at least 100 feet from the property line, effluent is disposed of on the property, and it is the only dwelling on the tract (30 TAC §285.3(f)(2); TCEQ OSSF permits page). What actually governs is the required absorptive/disposal area…

Question 4

Setback and separation distances under 30 TAC 285.91(10) — actual table numbers.

Accepted Answer

Table X distances are in feet, measured to the listed OSSF component (tank / soil absorption system & unlined ET / lined ET / watertight sewer pipe / edge of spray area / drip) (Figure: 30 TAC §285.91(10) Table X; Bandera County packet): From Tank Absorption / unlined ET Lined ET Sewer pipe Spray (edge) Drip --------------------- Public water wells 50 150 150 50 150 150 Public water supply lines 10 10 10 10 10 10 Private wells & underground cisterns 50 100 50 20 100 100 Wells completed per 16 TAC §76.1000(a)(1) 50 50 50 20 50 50 Private water line 10 10 5 10 (except at structure) no separation 10 Streams, ponds, lakes, rivers, creeks, retention ponds 50 75 50 (LPD w/ secondary + disinfection) 20 50 25 if Ra<0.1; 75 if Ra>0.1; 50 w/ secondary + disinfection Foundations, buildings, surface improvements, property lines, pools, other structures 5 5 5 5 none except property lines 20 and…

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