Standing water in a yard often leads owners to ask for a french drain. Sometimes that is the right fix, and sometimes a surface drain would work better. French versus surface drains is really a question of where the water is and how it moves.
Each system does a different job. Picking the wrong one can leave the problem in place after the work ends.
French Versus Surface Drains Explained
A surface drain catches water that flows across the ground or off paving. Grates, inlets or channels collect it and send it through solid pipe to a discharge point. This type handles runoff before it soaks in.
A french drain is a trench filled with gravel, usually with a perforated pipe near the bottom. Water from surrounding soil seeps into the gravel and pipe, then flows away. This type handles water already in the ground.
Where Surface Drains Fit
Surface drains suit puddles on patios, low spots in lawns and water flowing off driveways or roofs. Catch basins sit at low points. Channel drains run along the edge of paving.
Downspouts often connect to solid pipe that carries roof water away. That keeps large volumes from soaking soil near the foundation.
Jobs for French Drains
French drains suit soggy soil, seepage along a slope or wet areas behind retaining walls. They collect water spread through soil rather than water flowing on top. Each one also requires a discharge point below the trench.
The UC IPM page on landscape design and water quality mentions perforated drainage lines that filter water into soil. Some systems release water into the ground rather than to a street.
Telling the Problems Apart
Watch the site during and after a storm. Water sheeting across the surface and pooling at low points points to a surface drainage problem. Soil that stays soggy long after rain, with no visible flow, points to a subsurface problem.
A percolation test shows how fast water moves into soil. UC IPM describes the method on its aeration and soil pages.
When Grading Is the Real Fix
Many drainage problems come from poor grading. UC lawn soil preparation guidance advises grading so soil slopes away from the house. It warns against steep slopes or berms that increase runoff.
Regrading may solve a problem without any pipe. It often costs less than installing drains.
Outlets Decide Everything
Every drain needs a place for water to go. Gravity drains need an outlet lower than the inlet. Common outlets include a curb, a dry well, a rain garden or a lower part of the property.
Local rules may limit where drains can discharge. Check with the City of Sacramento before sending water to a street or neighbor’s lot.
Clogging and Sediment
French drains can clog when fine soil washes into gravel and pipe. Filter fabric around the gravel helps keep soil out. UF/IFAS Extension guidance on permeable paving notes that sediment carried in by runoff is a main cause of clogging, and the same principle applies to gravel drains.
Surface drains clog with leaves, mulch and debris. Grates need regular cleaning, especially under trees that drop leaves in fall.
Combining Both Systems
Many yards need both types. A channel drain may catch patio runoff while a french drain handles seepage from a slope. Each one should connect to a suitable outlet.
Avoid sending surface runoff into a french drain. Heavy runoff can overwhelm the gravel and carry in sediment.
Drains Behind Walls
Retaining walls often need drainage behind them. Water building up behind a wall adds pressure. Wall designs usually include gravel backfill, a drain pipe and weep holes.
The City of Sacramento requires permits for many retaining walls, with an exemption for walls not over 4 feet unless they carry a surcharge. Larger walls need engineering.
Trenching Near Trees
Trenching for drains can cut roots. UC IPM notes that most roots lie near the surface and many extend beyond the canopy. Route trenches away from large trees where possible.
The post on patios near tree roots covers root protection.
Buried Debris
Old concrete or rubble below the surface can block water and create soggy pockets. UC soil preparation guidance warns that construction debris impedes water movement. The post on buried landscape rubble explains what to look for.
Pool Decks and Patios
Pool decks and patios shed a lot of water. Channel drains along edges catch runoff before it reaches lawn or the house. The post on pool deck pavers covers that setting.
Utilities
Drain trenches cross many buried lines. Contact 811 before digging so utility operators can mark their lines. Private lines such as sprinklers need separate locating.
Dry Wells and Rain Gardens
Where no lower outlet exists, water may go into a dry well or a rain garden. UC IPM describes rain gardens as low areas that hold water briefly so it can soak in. Plants in them must handle both wet and dry periods.
Infiltration only works where soil drains well enough. Test soil before relying on a dry well in heavy clay.
Maintenance Over Time
Clean grates and catch basins each fall before the rainy season. Flush pipes with a hose if water backs up. Check outlets after big storms to confirm water is leaving freely.
Cleanouts at bends and ends make french drains easier to service. Ask for them in the design.
Signs a Drain Is Failing
Water that pools above a drain line, soggy soil returning in old spots or outlets that stay dry during storms suggest a problem. Sinkholes along a trench can mean pipe damage. A camera inspection can show what is happening inside the pipe.
Choosing a Contractor
Ask each bidder to explain what is causing the problem and why their solution fits. Bids should show trench depth, pipe type, gravel, fabric and outlet. The post on hardscape estimate comparison helps line up bids.
French versus surface drains is a diagnosis question before it is a construction question. More drainage topics sit in the concrete and drainage category.