Brentwood, CA · East Contra Costa
French Drain Repair in Brentwood, CA
A French drain that worked for years can quietly stop. Silt fills the gravel, roots get into the pipe, or the outlet gets buried. Here is how to tell what failed, what a repair involves, and when it makes more sense to replace the line.
Cited cost ranges · No obligation
Signs your French drain has stopped working
Water comes back where the drain is
Puddles or soggy ground right over the drain line after rain usually mean the pipe or gravel is clogged.
The outlet stays dry in a storm
If water is pooling in the yard but nothing comes out of the outlet, the line is blocked or crushed somewhere between.
Sinkholes or soft spots over the line
Soil washing into a broken pipe or a trench without fabric leaves depressions along the drain route.
The problem came back after a few seasons
Drains built without filter fabric in clay soil tend to silt up gradually. The yard slowly returns to how it was.
Why French drains fail
- Silt and clay fines. Without filter fabric, fine soil migrates into the gravel and the pipe. East County clay is fine-grained, so this is the most common failure here.
- Roots. Trees and shrubs seek out the moisture in a drain line, and roots can fill a perforated pipe.
- Crushed or separated pipe. Thin corrugated pipe can crush under vehicles or settle and pull apart at joints.
- No slope, or a sag. A line laid without steady fall holds water in the low spot, which then fills with sediment.
- A buried or blocked outlet. Landscaping, a new patio, or debris can cover the outlet so water has nowhere to go.
How a contractor finds the problem
The usual sequence is simple: run water into the cleanout or the high end and see where it comes out, if at all. A drain camera shows roots, silt, or a crushed section and its location, so only that part needs digging. Some contractors flush or hydro-jet the line first; if it runs clear afterward, that may be all it needs. If the camera shows the gravel itself is clogged with clay, flushing the pipe won't fix it, and the trench needs to be rebuilt.
Repair or replace?
| What the inspection shows | Usual fix |
|---|---|
| Debris or sediment in the pipe, gravel still clean | Flush or hydro-jet; add a cleanout if there isn't one |
| Roots in one section | Clear the roots; replace that section with solid pipe if a tree is close |
| Crushed or separated pipe in one spot | Dig and replace the damaged section |
| Buried or blocked outlet | Reopen or relocate the outlet; protect it from future landscaping |
| Gravel packed with clay, no fabric, line sags | Rebuild: new trench with fabric, gravel and pipe on grade |
What it usually costs
HomeGuide (February 2026) lists French drain cleaning at about $80–$500 or more. Angi's 2026 yard drainage data puts minor repairs at $200–$700 and major repairs at $1,000–$3,000. Replacing a failed section is priced like new installation: roughly $10–$50 per foot nationally and higher in the Bay Area (see the cost guide).
Published ranges, not a quote; Bay Area jobs often cost more than national averages. Full breakdown: French drain cost in Brentwood.
Keeping a French drain working
- Keep the outlet clear of mulch, soil, and leaves, and check that water flows from it during heavy rain.
- Flush the line through the cleanout every year or two, before the rainy season.
- Keep gutters clean if downspouts feed the drain; roof grit settles in the pipe.
- Plant trees well away from the drain line.
If you're deciding whether a drain is worth rebuilding at all, the trade-offs are in French drain pros, cons and alternatives.
Check any contractor, including one you find here
- Ask for the contractor's CSLB license number and look it up at cslb.ca.gov. The CSLB site also explains when a California contractor license is required.
- Get the quote in writing: the length and depth of each drain, the pipe and gravel, filter fabric, where the outlet is, and how the yard will be restored.
- Be wary of large deposits or cash-only terms. Ask who marks utilities through 811 and who handles any permit the city requires.
- Ask the contractor to show you the route and the fall from the farthest inlet to the outlet, and what warranty covers the work.
This site is an independent referral service, not a contractor. Your request goes to an independent local drainage contractor, who gives the quote and does the work. How this works
Common questions
How do I know if my French drain is clogged?
Water pooling over the drain line, a dry outlet during heavy rain, or the original problem returning are the usual signs. A contractor can confirm it by flushing the line and running a camera through it.
Can a clogged French drain be cleaned?
Often, yes, if the clog is in the pipe. Flushing or hydro-jetting clears sediment and roots. If the surrounding gravel is packed with clay because no fabric was used, cleaning the pipe won't restore it, and the trench usually needs to be rebuilt.
How long does a French drain last?
It depends mostly on how it was built: fabric, gravel quality, slope, and outlet. A well-built system can last for decades with occasional flushing; one built without fabric in clay soil can silt up within a few years.
How much does French drain repair cost?
Cleaning runs about $80–$500 or more (HomeGuide 2026); Angi's 2026 data puts minor repairs at $200–$700 and major ones at $1,000–$3,000. Rebuilding a section is priced like new installation. See the cost guide.
Related drainage fixes
French drain installation
Underground pipe and gravel that collects soggy-yard water and carries it to a real outlet.
Standing water & soggy yards
Work out what's causing the water, then match it to the right fix.
Hiring a drainage contractor
A quote checklist, the questions to ask, red flags, and how to check a license.
Downspouts & catch basins
Underground downspout lines, catch basins and channel drains for roof and patio water.
Talk to a local drainage pro
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