Most drainage problems announce themselves in January. A puddle on the patio that never seems to dry. A muddy trench where the downspout dumps onto the lawn. A damp smell in the crawl space, or a line of silt on the garage floor after a storm. In Kentfield, one of the wettest towns in the Bay Area, and on the shaded canyon lots of Fairfax, the ground is often saturated by Christmas and stays that way until spring.
Water on a property always goes somewhere. The question is whether it goes where you want it. Drainage work is about catching it, carrying it and releasing it in a safe place, whether that's a planting bed, a dry well or the street. Below are the signs a yard is draining badly, the main types of drainage fixes, how we track down and solve a problem, and why Marin's terrain makes all of this such a big deal. On sloped lots, the right drainage usually pairs with retaining walls that hold the hillside in place. Done well, the whole system is invisible: a few grates, a clean outlet, and a yard that's dry two days after a storm.
Signs Your Yard Isn't Draining
Look for water that stays put. Puddles that last more than a day after rain, soggy lawn that squishes underfoot for weeks, or moss and algae spreading across a shaded patio all mean water has nowhere to go. Watch the house too. Water stains or efflorescence, the white chalky crust, on the foundation, a damp or musty crawl space, cracked stucco near the ground, or doors that stick more in winter can all trace back to water pooling against the house. Downspouts that empty right at the foundation are one of the usual culprits. On slopes, look for soil washing onto paths, small gullies forming in planting beds, or mud collecting at the foot of the slope after every storm. Neighbors can be part of the picture too: runoff from an uphill lot often crosses property lines, and the fix has to account for water you didn't create.
French Drains, Catch Basins and Grading
Every drainage fix uses some mix of a few basic tools. Regrading reshapes the soil so the ground falls away from the house and water heads somewhere useful on its own. It's often the cheapest fix and the one people skip. A French drain is a trench filled with gravel around a perforated pipe, wrapped in filter fabric, that collects water seeping through the soil and carries it off. A catch basin is a grated box set at a low spot to collect surface water from a patio or lawn and feed it into a solid pipe. Downspout lines connect gutters to buried pipe so roof water never lands next to the house. A dry well is an underground pit or chamber where collected water can soak slowly into the ground. Most yards need two or three of these working together.
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Call [TRACKING NUMBER]How We Find and Fix Drainage Problems
We start by watching the water, ideally during or right after rain. We trace where runoff enters the property, where it collects and where it's trying to go. We check the downspouts, the slope of the ground near the foundation, and any old drains that may be clogged or crushed. Then we lay out a plan: where pipe needs to run, where it can safely let water out, and what grading has to change. Before we dig, utilities get marked through 811. We install pipe with steady fall so water keeps moving, use clean gravel and fabric so the system doesn't silt up, and add cleanouts so lines can be flushed later. When we're done, we run water through the system to prove it works, and we give you a simple sketch of where the lines and cleanouts are so nobody digs through them later.
Why Drainage Matters So Much in Marin
Marin's mix of steep hills, heavy clay and concentrated winter storms makes drainage a bigger deal here than in most of the state. Clay soaks up water slowly, so rain that would vanish into sandy soil runs across the surface instead. Hillsides send that runoff downhill toward houses, patios and walls. And when a big storm parks over the county for several days, every weak spot shows up at once. Poor drainage is behind a lot of the damage people blame on other things: cracked patios, leaning walls, rotting fence posts, mildew in the crawl space. Fixing the water usually fixes the rest, and doing it before the rains start is far easier than working in mud in February. Fall is the best window: the ground is dry enough to dig cleanly, and the new system is in place for the first real storm.
If water has been sitting on an old patio for years, the fix often includes rebuilding it with the right slope, and our patio and hardscape work handles both at once.
Common Questions
A French drain gives water an easier path than the soil around it. It's a trench lined with filter fabric, filled with gravel, with a perforated pipe running along the bottom. Water in the surrounding soil flows into the gravel, drops into the pipe through its holes, and runs downhill to an outlet like a dry well, a planting area or the street. The fabric keeps silt out so the system keeps working for years instead of clogging.
For most yard drainage, a French drain sits somewhere around a foot and a half to two feet deep. A drain meant to protect a foundation or a crawl space usually goes deeper, closer to the level of the footing. The more important number is the slope: the pipe needs a steady fall along its length so water keeps moving instead of sitting in it. On Marin hillsides, the slope is rarely the problem. Finding a safe place to let the water out is.
Not much is needed if it was built right. Keep gutters clean so leaves don't wash into connected lines, keep the outlet clear of debris and plants, and check after the first big storm each winter that water is flowing out. If the system has cleanouts, flushing the lines with a hose every couple of years clears out any silt. A drain that suddenly stops working usually has a crushed pipe or a blocked outlet, both of which can be found and fixed.