A french drain collects water diffusely along its entire buried length—right for soggy ground, saturated lawns, and subsurface seepage toward a structure. A catch basin captures surface water pooled at one low point and pipes it away. The wrong system for the wrong problem either does nothing or costs far more than needed. Identify what your water is actually doing before choosing a solution.
The distinction between a french drain and a catch basin is simpler than most drainage guides make it sound. A french drain is a perforated pipe buried in a gravel trench. Water enters it along the entire trench—seeping through the surrounding gravel from saturated soil, entering the perforated pipe at multiple points, and running to the outlet. The system works because water is moving through the ground diffusely, spread across an area. The whole length of the trench participates in collection, not just one spot.
A catch basin is a box with a grate set at a specific low point on the surface. Water runs across a hard surface or lawn until it reaches the grate, falls into the box, and exits through a pipe connected to an outfall. The system works because surface water has concentrated at one identifiable point. The catch basin collects only what reaches that grate. The pipe carries it away from there.
Those two mechanisms match two fundamentally different drainage problems. A soggy lawn that never fully dries in spring, a hillside that stays wet through June, water showing up at a foundation wall, or a planting bed that remains saturated long after rain has stopped—these are diffuse subsurface water problems. The water is moving through and accumulating in the soil across a wide area. A french drain is the right tool because it can collect along its full run rather than waiting for water to concentrate at one surface point that a basin grate could intercept.
A single low spot in a driveway that ponds during rain, a corner of a patio that holds water after every storm, or a location where a downspout discharges concentrated roof runoff at one point—these are surface concentration problems. The water is arriving fast, building up on the surface, and pooling in one location. A catch basin is the right tool because it intercepts that surface water at the point of concentration and pipes it away before it can spread. Clark County's low-elevation areas around 49 feet near Salmon Creek can be flat enough that both systems require careful thought about where the discharge pipe ultimately outlets—flat ground gives water nowhere easy to go.
More on drain types across Clark County.
A french drain for a typical residential run of 100–150 feet in Clark County costs $1,800–$5,500 installed, depending on trench depth, soil conditions, access for equipment, and how far the outlet pipe must run to reach a legal discharge point. The county's clay-heavy soil takes longer to trench cleanly than sandy or loamy ground, and the dry window from mid-June through September is when the trench walls hold best and the work goes fastest. Longer runs or deeper trenches to reach adequate slope move cost toward the upper end of that range.
A catch basin installation for a single low-point problem is often less expensive because the excavation footprint is smaller—one box, backfill, and the outlet trench. The cost is driven primarily by how far the outlet pipe must run and what the outfall situation is. Running a four-inch pipe forty feet to a ditch is a simple job. Running it two hundred feet across difficult terrain to reach a legal outlet is substantially larger.
Equipment and operator time runs $110–$190 per hour regardless of which system is being installed. Both projects land in the $1,500–$6,500 range for most residential scopes, with the outlier being when there is no viable gravity outfall. When the lot is low and flat and there is nowhere for water to go downhill, a sump and pump become part of the design, adding equipment cost and an ongoing electrical connection to run it.
Vancouver Excavation Co. covers the rest of Clark County.
The failure mode people hit most often is installing a catch basin in ground that is diffusely saturated. The reasoning sounds sensible—"I have a drainage problem, I will put a drain in"—but the catch basin is waiting for water to concentrate at its grate, and that concentration never happens. The surrounding soil is saturated, but the surface water is not pooling specifically at the basin location; it is moving through the soil everywhere around it. The basin grate stays dry while the yard remains wet. This is not a cheap mistake—a catch basin installation is real money, and removing it to install a french drain instead nearly doubles the total cost.
The inverse mistake is installing a french drain beneath a single hard-surface ponding point. A driveway low spot that ponds during a hard rain is a surface concentration problem. A french drain buried beneath it will move some water via subsurface infiltration, but it is not designed to handle fast surface inflow at a single point—its mechanism is slow distributed collection over a long run. The pond may improve slightly or not at all. A correctly sized catch basin with an adequate outlet pipe would have solved the problem directly at a lower cost.
The third common mistake is assuming an outfall exists before the system is designed. Both a french drain and a catch basin require somewhere legal and lower to discharge to. On flat, low ground at the elevations found near Salmon Creek, gravity outfall can be difficult or impossible without a pump. Before committing to either system, the first question is: where does the water go when it leaves the drain? Is that destination lower, is it on your property or a legal discharge point, and can a pipe reach it? Answering that question before installation prevents costly surprises when the outlet trench is already open.
Small drainage problems—a minor low spot that holds water briefly after rain, a short swale that needs reshaping to redirect runoff—can often be handled by a homeowner willing to rent a trencher and spend a weekend on it. The key is correctly diagnosing whether you have a surface concentration problem or a subsurface saturation problem before buying materials or renting equipment. Getting the diagnosis wrong and installing the wrong system is more expensive than spending an hour on a professional site visit to confirm the right one from the start.
Call a drainage contractor when the wet area is large, when the same ground has been problematic for multiple seasons, when water is reaching a foundation or other structure, or when you cannot find an obvious outfall by walking the property. Drainage work that crosses permit thresholds—which most jurisdictions determine by scope of soil disturbance— also requires a licensed contractor who can carry the work through inspection. Clark County's permit office will tell you whether your planned drainage project needs a permit when you describe the scope; that call takes about five minutes.
RCW 19.122.030 applies to drainage work exactly as it does to any other excavation. Mark the proposed work area in white before anything else, call 811 at least two full business days before any digging begins, and wait for utilities to be located and marked. A french drain trench can cross an unmarked communications line. A catch basin excavation can hit a gas lateral. The 811 locate process is free and mandatory for homeowners and contractors alike—it is not optional even for shallow drainage work.
How we handle drain types in the field.
A soggy lawn across a wide area is almost always a subsurface saturation problem—water moving through and sitting in the soil rather than pooling at one surface point. A french drain is designed for exactly this: it collects diffuse subsurface water along its entire length and carries it to an outfall. A catch basin waits for water to concentrate at a grate, and in saturated ground that concentration never happens—the basin would likely do little for a persistently wet lawn.
A catch basin. The problem is surface water concentrating at one point, and a catch basin is designed to intercept it at the grate and pipe it away. A french drain handles diffuse subsurface water over a long run—it is not the right tool for a single concentrated surface-ponding point on a hard surface, and installing one there would cost more and likely solve less of the actual problem.
Both systems need a legal discharge point—somewhere lower than the drain that accepts the water without directing it onto a neighbor's property. Common outfalls are a roadside ditch, a storm drain connection approved by the jurisdiction, or a safe daylight point on your own property. On flat, low-elevation ground in Clark County, an adequate gravity outfall sometimes does not exist, and a sump pump becomes a necessary part of the drainage design.
A short, shallow french drain to redirect water away from a foundation or wet corner of a yard is within a motivated homeowner's reach—rent a walk-behind trencher, lay perforated pipe in drainage rock, and outlet to a lower point. The difficulty is usually diagnosis and finding a legal outfall. Call 811 first under RCW 19.122.030. Longer runs, deeper trenches, or work near structures are worth getting a professional estimate on before committing to the approach.
It depends on the scope and the jurisdiction. Minor drainage improvements often fall below permit thresholds. Work that disturbs a larger area, connects to a public storm drain, or is near a critical area may require a permit from Clark County or your city. Call the permit office and describe your planned work—they will tell you quickly whether it crosses the threshold. Permit thresholds vary by jurisdiction and are not reliably published online; confirm directly.
The diagnosis comes first—tell us where the water is showing up and what the ground looks like between wet weather and dry, and we will tell you which system makes sense and what it will cost. We do site visits across Clark County and the surrounding cities before putting a number on paper.