DeSoto, TX Environmental Rules: Grading & Drainage (2026)

DeSoto requires grading and drainage plan review for new construction, major additions, and significant site modifications. Drainage plans must demonstrate that post-development runoff does not adversely impact adjacent properties and that lot drainage directs water away from foundations and toward approved discharge points (street gutter, approved swale, or detention facility). Texas law recognizes the 'civil law' rule for surface drainage — the upper property owner has a natural easement for flow across lower properties, but that flow cannot be artificially increased or redirected without the lower owner's consent. Regrading that diverts water onto a neighboring property can result in civil liability and code enforcement action. For larger developments, DeSoto requires detention or retention facilities sized per the iSWM (integrated Stormwater Management) design manual commonly used in the DFW region, with release rates not exceeding pre-development conditions. Foundation drainage must slope at least 6 inches in the first 10 feet away from the structure per IRC.