Setback and separation distances under 30 TAC 285.91(10) — actual table numbers.
State rules are the floor. Figures here are TCEQ minimums under 30 TAC Chapter 285. Your county can be stricter and around here most are — check your county before you rely on a number.
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 pools 25 | none except property lines 5 |
| Underground easements | 1 | 1 | 1 | 1 | may spray to edge, not into; heads 1 ft from edge | 1 |
| Overhead easements | 1 | no setback with easement-holder permission | 1 | no setback with permission | 1 | no setback with permission |
| Slopes where seeps may occur, detention ponds | 5 | 25 | 5 | 10 | 10 | 10 if Ra<0.1; 25 if Ra>0.1 |
| Edwards Aquifer recharge features | 50 | 150 | 50 | 50 | 150 | 100 if Ra<0.1; 150 if Ra>0.1 |
Footnotes: the 20-foot spray-to-property-line distance drops to 10 feet when sprinklers are on a commercial timer per §285.33(d)(2)(G)(i); drip lines may not be placed under foundations; and no OSSF may be within 75 feet of the banks of the Nueces, Dry Frio, Frio or Sabinal Rivers downstream of the northern Uvalde County line to the recharge zone (Table X footnotes). Table X sets no driveway-specific number — driveways fall under "surface improvements" at 5 feet for tanks and fields (Bandera County packet); a distinct "driveway/parking" line item is n.a. Counties may be stricter: Hays County requires 40 ft from spray areas (60 ft from individual sprinkler heads) to property lines, habitable structures and food gardens, scaling to 75 ft and 90 ft for larger sprinkler radii, plus a 100-ft private-well setback (Hays County OSSF Regulations), and Washington County requires 25 ft from spray edge to structures/property lines and 75 ft to waterways (Washington County OSSF Order 2025).
Check this one before you rely on it. These distances are transcribed from the archived Texas Register figure and a county reproduction of the same table rather than a TCEQ-hosted copy, and one secondary extraction disagrees on the spray-to-private-well cell. Confirm against the current TCEQ figure and your county order before you site anything from this table.
Reviewed August 2026. Links go to the sources this answer was checked against.
More on design & engineering
- What a site evaluation is and what the evaluator actually tests and documents.
- Soil profile analysis vs percolation test — which Texas requires, when each is allowed, how each is performed under 30 TAC 285.
- How design loading rate translates into drainfield square footage or spray-area size.
- When a Professional Engineer's seal is required on the design instead of a site evaluator's or installer's plan.
- Designing around hard site limits: shallow bedrock, high water table, steep slope, restrictive horizon, tight lot.
- Spray field layout — required coverage area, keeping spray within property, landscaping and planting restrictions over the field.
All design & engineering questions · County permitting offices