Drainage That Works for Hill Country Homes

A Hill Country drainage guide for grading, swales, and erosion control.

Read the land: grading, swales, and safe water paths

Every great Hill Country home starts with water moving the right way—around the house, not through it. Begin by reading the land before you design. Walk the lot after a rain to see natural flow paths, shallow depressions, and eroded edges; compare those observations with a current topographic survey. On new construction, aim to shape a gentle, continuous slope away from the home, using broad, shallow swales to gather and guide runoff toward safe outlets. Keep swales vegetated or lined with stone to prevent erosion, and avoid sending concentrated flow toward neighboring properties or driveway entrances. Where do swales empty? Plan daylight points with rock aprons or level spreaders that dissipate energy before water enters natural areas. If you need to capture water near foundations, consider French drains—perforated pipe set in gravel with filter fabric—only as part of a larger grading plan; drains alone won’t fix a negative slope. On rocky lots, shallow soils make “cut and fill” decisions more consequential: lift the pad where needed with compacted, tested fill and shape transitions with short, well‑vegetated slopes to resist erosion. For background on small residential stormwater controls—what they are and why they matter—see general program information at the EPA’s stormwater portal: EPA NPDES stormwater program. Roof water is a major input. Size gutters and downspouts for local rainfall intensity, and avoid dumping multiple downspouts in a single corner. Where you want to harvest rainwater (common in the Hill Country), integrate collection with drainage: screened gutters feed first‑flush diverters and tanks, while overflow routes to the same stable outlets you designed for storm events. Remember that rainwater tanks, pads, and piping must sit out of foundation drainage paths. If driveway or pool plans change grading later, update your swale routes and outlet protection so you don’t accidentally send water toward the house. Before earthwork, protect undisturbed areas and tree root zones. Install silt fence on downhill edges and a stabilized construction entrance to minimize sediment tracking—these simple measures keep your site workable and neighbors happy while you rough‑grade.

Foundations, driveways, and erosion controls that last

Driveways and structures are where drainage details get tested. Start with foundations. Grade to fall away from the home on all sides, target at least 6 inches of drop within the first 10 feet where site constraints allow, and use downspout extensions or tightlines to keep roof runoff off slabs and piers. On sloped sites, create interceptor swales or area drains upslope so hillside water skirts the pad rather than cutting across it. Photographs of under‑slab drains, vapor barriers, and perimeter drains are worth their pixels during inspections and when selling later. Driveways concentrate water; design them as small civil‑engineering projects. Crown or cross‑slope gravel drives to shed water quickly and place shallow ditches (bar ditches) with rock checks at intervals to slow flow. For a comprehensive, practical reference on crowning, drainage, and maintenance of unpaved roads, keep this FHWA guide handy: FHWA Gravel Roads Construction and Maintenance Guide (PDF). Where driveways drop to meet a road, size culverts for peak events and protect inlets and outlets with rock riprap to prevent erosion. Erosion and sediment control isn’t just for big subdivisions. Even a single rural home can discharge muddy water into neighbors’ ditches or creeks. Install silt fences on the downhill side of disturbed soil, maintain stabilized construction entrances, and add straw wattles or rock checks where runoff concentrates. Texas summarizes construction stormwater requirements and the threshold for a SWPPP here: TCEQ: Construction Stormwater Permit Overview; the EPA’s background on construction stormwater discharges is here: EPA: Construction stormwater discharges. On rocky slopes, protect outlets where French drains or downspouts daylight with rock aprons so you don’t scour soil during storms. Finally, integrate landscape with drainage. Choose native grasses and groundcovers that knit soil, and stabilize bare areas quickly after heavy sitework. Where you want lawn, contour edges so mowing doesn’t scalp swale banks. Small retaining walls should include drainage blankets and weep holes; without them, hydrostatic pressure can defeat even well‑built walls after a single big rain.

Permits, inspections, and maintenance after move‑in

Drainage success continues after you move in. Start with records. Keep a site plan that shows swales, under‑drains, culvert sizes, and daylight points. After major storms, walk the property to spot erosion, sediment build‑up at inlets, and standing water near foundations. Clear leaves from inlets, re‑set displaced rock, and re‑seed bare spots—small touch‑ups prevent big repairs. Know when permits and inspections apply. In city limits or certain ETJs, new impervious area (additions, big patios, pools) can trigger drainage reviews. If your driveway ties into a state‑maintained road, culvert work may need state approval; Texas’ access standards and permit process are summarized here: TxDOT driveway permits, design, and materials. For rural access road drainage standards you can scale to residential use, engineers often reference USDA NRCS guidance: USDA NRCS Access Road Standard (Code 560). On steep Hill Country sites, consider periodic third‑party checks—your builder or a civil engineer can review whether swales still pitch correctly and whether landscape changes (mulch berms, beds) are blocking flow. Keep gutters clean, verify downspout ties aren’t crushed, and refresh rock at splash zones before spring storms. A final Texas‑smart tip: coordinate drainage with dark‑sky and wildfire‑wise landscaping. Rock aprons and gravel borders double as noncombustible zones near the house, and warm, shielded path lights preserve night vision without attracting insects around swales and outlets. With a simple maintenance rhythm and records in your binder, your site will move water safely for decades.