French drain vs sump pump

French drain vs sump pump: passive gravity drainage vs active pumping. Compare installation costs, best use cases, and when you need both for water management.

A French drain is a passive drainage system: a gravel-filled trench with a perforated pipe that collects groundwater or surface water and redirects it by gravity to a lower discharge point — a storm drain, dry well, or daylight outlet. Installation costs $1,000–$10,000 depending on length (typically $20–$50 per linear foot), depth, soil conditions, and whether it's exterior (yard) or interior (basement perimeter). Exterior French drains intercept water before it reaches the foundation; interior systems collect water that has already entered and channel it to a sump pit. French drains have no moving parts, no electricity cost, and minimal maintenance (occasional flushing every few years). A sump pump is an active system: a pump sits in a pit (sump basin) below floor level and automatically activates when water rises to a set level, pumping it out through a discharge pipe to the exterior. Installation costs $800–$2,500 for a basic system (pit, pump, discharge line, check valve) and $1,500–$4,000+ for a battery-backup or water-powered backup system. Operating cost is $30–$50/year in electricity for typical use. Sump pumps are essential in areas with high water tables, heavy seasonal rain, or existing basement flooding where gravity drainage alone can't keep up. The systems are often complementary, not competing: many basement waterproofing jobs install an interior French drain around the perimeter to collect water and route it to a sump pit, where the pump ejects it. Exterior French drains handle yard grading and surface water. The right choice depends on where the water is and whether gravity can move it out.