Drainage Correction & Swale Installation
in San Marcos, TX
San Marcos Elite Grading & Excavation has been correcting drainage and installing swales in the San Marcos, TX area for over 20 years! Drainage correction is the process of identifying and resolving the specific grade defects, drainage system failures, and surface water management problems that cause water to accumulate where it should not — against foundations, in low areas of yards, along shared property lines, and in driveways and garages. In San Marcos and throughout Hays County, drainage correction is one of the highest-demand services we provide, driven directly by the behavior of blackland prairie clay soil that dominates the eastern portions of the city. We provide drainage correction and swale installation services for residential and commercial properties throughout San Marcos, Kyle, Buda, Wimberley, New Braunfels, Dripping Springs, and surrounding Hays County communities.
Swale installation is the most cost-effective surface drainage correction tool available on most residential sites — a properly designed and graded swale channel moves water off a property faster and more reliably than any surface coating, barrier, or absorption system applied to soil that cannot absorb water fast enough to keep up with Central Texas storm events. San Marcos receives an average of 36.55 inches of rainfall annually, with peak monthly totals in May and September regularly exceeding 4 inches — and that rainfall arrives in high-intensity events that deposit several inches in a matter of hours, not days. A drainage system designed only for average conditions fails every time an above-average storm hits. We design swale systems for the peak hydraulic load the site will actually experience, not the average. Written, fixed-price quotes are provided after a no-charge site visit.
Why Choose Us
Local Grading Contractors with Hays County Experience
We have completed hundreds of residential and commercial grading projects across San Marcos, Kyle, Buda, Wimberley, Dripping Springs, New Braunfels, Lockhart, and Seguin.
Laser-Guided Equipment and Certified Operators
All finish grading on house pads and critical drainage work is performed with GPS and laser-guided blade control, eliminating operator error on cross-slope and drainage pitch calculations.
Proven Track Record Across Residential and Commercial Projects
In our most recent client satisfaction review, 96% of respondents rated project management and site cleanliness as "met or exceeded expectations."
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Drainage Correction & Swale Installation Services We Provide
Drainage System Diagnosis and Site Assessment
Effective drainage correction begins with an accurate diagnosis of what is actually causing the problem — not a surface observation of where water is pooling. We conduct a full site assessment using digital survey equipment to map existing grades, identify drainage collection points, trace the flow path of surface water across the property, and determine whether the root cause is a grade defect, a blocked or undersized drainage outlet, an uphill drainage contribution from neighboring properties, or a combination of all three. Treating the symptom without diagnosing the system produces corrections that move the problem rather than solve it — water pooling shifts from one location to another without ever leaving the property. Our drainage assessments document existing conditions in sufficient detail to design a correction that addresses the full drainage system, not just the visible failure point.
Surface Regrading for Drainage Correction
The majority of residential drainage problems in San Marcos trace back to one of three grade conditions: a flat grade around the foundation perimeter that allows water to pond rather than drain, a negative grade that slopes toward the structure rather than away from it, or a low area in the yard that collects water from multiple directions with no outlet. Surface regrading corrects these conditions by reshaping the lot surface — adding fill to raise low areas, cutting high spots that block drainage flow, and establishing a consistent positive slope that moves water toward the street, a drainage easement, or a swale channel. The International Residential Code requires a minimum 6-inch drop over the first 10 horizontal feet from any foundation — on blackland clay, meeting this minimum is the baseline, not the ceiling. We establish finish grades with laser-controlled equipment, holding tolerances within one-tenth of a foot to ensure the corrected grade performs as designed.
Swale Design and Installation
A drainage swale is a shallow, linear channel graded into the lot surface to intercept and convey concentrated surface runoff from one point to another. Swales are the primary surface drainage conveyance tool on residential properties — they carry water that the lot grade collects and routes it to an approved outlet location. The EPA recognizes vegetated swales as a proven stormwater Best Management Practice for controlling runoff velocity and volume while reducing erosion and sediment discharge. We design swales to the hydraulic dimensions required by the drainage load they carry — bottom width, side slopes, and longitudinal grade are all calculated based on the watershed area draining to each channel and the design storm flow that the swale must convey without overtopping or eroding. Swales installed without hydraulic sizing calculations are frequently undersized for the loads they receive and fail at the first significant storm event.
Shared Property Line Drainage Correction
Drainage conflicts along shared property lines are among the most common and most contentious drainage problems on residential lots in San Marcos. Uphill neighbors whose lots drain onto downhill properties, fences that block natural drainage flow, and shared swale easements that have been filled or obstructed all create drainage problems that cannot be fully resolved by regrading only the affected lot. We assess the full drainage system affecting a property — including off-site contributions from adjacent lots and the street — and design corrections that manage the total water load reaching the site, not just the water originating on it. Where shared drainage easements are involved, we advise on the easement documentation requirements that protect the correction from being blocked or altered by neighboring property owners in the future.
Downspout and Roof Drainage Integration
Roof drainage from gutters and downspouts is frequently the largest single source of concentrated water discharge on a residential lot — a 2,000 square foot roof in a 1-inch rain event sheds approximately 1,250 gallons of water. When downspouts discharge at grade against a foundation on blackland clay, that volume saturates the soil immediately adjacent to the slab perimeter and drives the wet-dry cycle that produces differential foundation movement. We integrate downspout discharge into the swale system or route it through buried pipe extensions that carry roof drainage away from the foundation zone before it reaches grade. Downspout management is frequently the highest-impact single correction available on a residential drainage problem and is included in every drainage correction scope we design.
Outlet and Outfall Correction
A drainage system that moves water efficiently across a property still fails if the outlet — the point where water leaves the property — is blocked, undersized, or discharges to a location that backs up during storm events. Common outlet failures on San Marcos residential lots include blocked curb cuts that prevent drainage from reaching the street, undersized or collapsed culverts under driveways, and swale outlets that terminate at a fence line rather than at an approved drainage point. We identify and correct outlet failures as part of the drainage correction scope — a swale that drains to a blocked outlet is not a drainage solution.
Types of Properties We Serve
Residential Lots with Foundation Drainage Problems
Residential properties with water intrusion, foundation movement, or persistent wet areas adjacent to the structure are the primary application for drainage correction services in San Marcos. These properties typically have one or more of the grade defects described above — flat or negative grade around the foundation, blocked swale channels, or inadequate downspout management — that have been allowing water to accumulate against the slab perimeter through multiple rain seasons. The damage accumulates silently: foundation movement that begins as a hairline crack in drywall progresses to sticking doors, sloping floors, and ultimately to structural repair costs that dwarf the cost of the drainage correction that would have prevented it.
Established Neighborhoods with Aging Drainage Infrastructure
Older San Marcos neighborhoods — particularly those near Purgatory Creek, Cottonwood Creek, and Willow Springs Creek — developed under drainage standards that predate current code requirements and were designed for lower impervious cover densities than exist today. As infill development, additions, and landscaping changes have accumulated over decades, the drainage systems in these neighborhoods have been progressively overwhelmed. Properties in these areas frequently experience drainage problems that are partly attributable to neighborhood-wide system capacity issues, not just individual lot grade defects. We diagnose these system-level contributions during the site assessment and design corrections that manage the water load the site actually receives.
New Construction Lots with Grading Deficiencies
Production builder lots and custom home sites where the initial grading did not meet the drainage performance standard required by the soil conditions are a significant source of drainage correction demand in San Marcos's growth areas. Grading deficiencies on new construction lots are often not apparent until the first significant rain season after occupancy — the lot looks flat and finished, but the grade is insufficient to move water away from the foundation on blackland clay. We correct new construction drainage deficiencies using the same regrading and swale installation methods applied to established lots, with documentation of the corrected grade conditions provided to the homeowner.
Commercial Properties with Stormwater Management Requirements
Commercial properties along the I-35 corridor and in San Marcos's business districts must manage stormwater runoff in compliance with the City of San Marcos's drainage ordinance and, where applicable, TCEQ stormwater permit requirements. Drainage correction on commercial sites involves larger impervious cover areas, higher runoff volumes, and more complex regulatory compliance requirements than residential drainage work. We execute commercial drainage correction scopes with the engineering coordination and permit documentation that commercial project requirements demand.
Some of Our Customer Reviews
"We had water against our foundation every time it rained. San Marcos Elite came out, surveyed the whole lot, and showed us exactly where the grade was wrong. Two days of work and the problem was gone. Wish we had called sooner."
— Linda M., San Marcos, TX
"They regraded the swale along our back fence line and extended our downspouts into the system. First hard rain after — all the water that used to pool behind the house was gone in twenty minutes."
— Gary & Susan T., Kyle, TX
"The drainage problem on our lot was coming from two neighbors uphill. They designed a correction that handled all of it, not just the water from our own roof. That's the difference between a real diagnosis and a band-aid."
— Rachel H., Buda, TX
"Commercial property on the I-35 frontage road — standing water in the parking lot after every rain. They regraded the lot, installed a swale along the back property line, and coordinated the outlet connection with the city. Problem solved, permit closed."
— James D., San Marcos, TX
Drainage Correction & Swale FAQs
How do I know if my drainage problem needs regrading, a swale, or a French drain?
Surface regrading and swale installation address surface water — rainfall and runoff that is not moving off the lot correctly due to grade defects or missing conveyance channels. French drains address subsurface water — water moving through the soil profile and accumulating below grade against foundation walls or in low areas where the water table rises after rain events. Most drainage problems on San Marcos residential lots are primarily surface water problems caused by grade defects, making regrading and swale installation the appropriate first correction. The site assessment will determine which solution — or combination — applies to your specific conditions. Properties with persistent wet areas that remain saturated for days after rain events, even in areas with adequate surface grade, typically have a subsurface component that requires French drain installation in addition to surface corrections.
How long does drainage correction work take on a typical residential lot?
Most residential drainage correction projects — regrading and swale installation on a standard San Marcos residential lot — are completed in one to two days. Projects that involve significant fill volume, multiple swale channels, or downspout integration work may run two to three days. We provide a written project timeline at contract signing based on the site assessment and the correction scope required.
Will the corrected swale affect my landscaping?
Swale installation requires reshaping the lot surface along the swale corridor, which typically involves removing and replacing sod or ground cover in the affected area. We minimize disturbance to existing landscaping outside the swale footprint and restore the swale surface to a condition ready for turf re-establishment after grading is complete. Swales are designed with side slopes and bottom widths that allow standard mowing without difficulty once turf is established — typically 3:1 side slopes or flatter.
Can you fix a drainage problem that is caused by my neighbor's lot draining onto my property?
We can design and install drainage corrections that manage the water load your property receives regardless of its source — including runoff from uphill neighbors. The correction typically involves intercepting the off-site drainage contribution with a swale or French drain along the uphill property line and routing it to an approved outlet before it reaches the problem area. We cannot alter grades on neighboring properties without the neighbor's consent, but we can design a system on your property that manages the water you receive. Where a drainage easement exists along a shared property line, we advise on the legal documentation that protects your correction from future obstruction.
Do drainage correction projects require a permit in San Marcos?
Permit requirements for drainage correction work depend on the scope and location of the project. Projects within the City of San Marcos that involve significant grade alteration or drainage system modification may require a grading or drainage permit from the Development Services Department. Smaller residential regrading and swale projects that do not exceed the city's permit thresholds typically do not require a permit. We verify permit requirements for every project during the site assessment and handle permit coordination where required.