What drain tile is for, and which fixes come first
A French drain or drain tile collects water below the ground surface and carries it to a place where it can leave.
Expansive clay moves as it wets and dries, a 2024 SCAG regional report says. For watering, an expansive-soils sheet from Colorado State University Extension that Monterey Park posts advises sprinklers no closer than 5 feet to a foundation and trees at least 15 feet away.
What drainage work costs in California: the evidence we can show
Our estimate for a drainage project is $2,800 to $21,800 per project, and the table also gives a range per linear foot for an exterior French drain. They are models and not quotes, from two national published ranges adjusted by California's construction laborer wage ratio, with no counted California company price behind them.
| Item | Figure | What it is |
|---|---|---|
| Estimated range, not a quote | $2,800 to $21,800 per project | Built from 2 national published ranges, adjusted by the California construction laborer wage ratio (1.25). Two California foundation companies publish prices (Quartz Construction in San Jose, a range table; Avalon Structural near San Jose, inspection fees); that is too few to anchor a California range, so no company price moves the estimate. Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Estimated range per linear foot, not a quote | $12 to $53 per linear foot, exterior French drain | Built from 2 national published ranges, adjusted by the California construction laborer wage ratio (1.25). Two California foundation companies publish prices (Quartz Construction in San Jose, a range table; Avalon Structural near San Jose, inspection fees); that is too few to anchor a California range, so no company price moves the estimate. Basis: no state company sample (no counted California company price for this job), national estimate only. |
Estimated range. Built from national published ranges (2 sources), adjusted by California's construction laborer wage ratio to the US (1.25, BLS May 2025). Not a quote. Only two of the 18 California foundation companies we looked at publish a price we could count, so no company price anchors the estimates. We have no counted California company price for this job, so the range is our national estimate alone. Full method. Prices as of Oct 23, 2026.
Landslide zones and the recent storm declarations
FEMA's declarations for the 2023 winter storms (DR-4683, DR-4699) and April 2024 (DR-4769) named flooding, landslides and mudslides across 44, 46 and 9 designated areas. The California Geological Survey maps landslide zones. Check yours on EQ Zapp before you decide where a drain empties.
Call 811 before trenching
Gov. Code 4216.2 asks an excavator to notify the regional notification center at least two working days and no more than 14 calendar days before digging, except in an emergency. The area has to be marked first, the 24 inches either side of a marked line are dug by hand tool, and the service is free. A homeowner digging on private property may contact the center where the property contains someone else's underground lines.
USA North 811 serves 49 northern and central counties, including Alameda, Contra Costa, Fresno, Kern, Monterey, Sacramento, San Francisco, San Joaquin, San Mateo, Santa Clara, Sonoma, Tulare and Yolo. DigAlert serves southern California, including Los Angeles, Orange, San Diego, Riverside, San Bernardino, Ventura, Santa Barbara and Imperial counties. Utilities mark only the lines they own, so private irrigation and yard lighting are not marked.
Who may do the work
By their definitions, C-42 covers storm drains and other sewage disposal and drain structures including the pipe laying, C-27 landscaping covers grading for landscape systems, C-12 covers trenching and grading, and the C-61 list includes D-56 for trenching only. That mapping is our interpretation. Ask the contractor which class it holds and why it fits.
At $1,000 or more, or whenever a permit or hired workers are involved, the contractor must hold a CSLB license. Look the number up on CSLB's Check a License page before you sign.
Confirm the cause before buying a drain
The company that diagnoses the water often sells the drain. Ask where the water comes from, where the drain will empty, and what the company would do if the discharge point turned out to be off limits. The sources we have set no California rule on where a yard or perimeter drain may discharge, so your city or county is the one to ask.
When a drainage problem can't wait
- Water is rising inside during a storm and the pump isn't keeping up.
- Water has reached the panel or outlets: stay out of it and call 911 or your electric utility.
- A wall is shifting while water presses on it.
- Walls that feel damp after a storm and then dry out.
- A downspout that empties close to the wall, on a dry day.
Checks to make before a drainage call
- Walk the outside during rain and note any downspout that ends within a few feet of the wall.
- Note whether the ground next to the house slopes toward it.
- Ask your city or county where water from your lot may be sent before you plan a drain.
Permits for drains and where the water ends up
Your city or county decides whether a drain needs a permit and where it may discharge, and the sources we have address neither. Ask the office before you plan the line, then call 811 before the trench.
Ask for the contractor's license number and check it with your state licensing agency before you sign anything.
Questions people ask
Where can a French drain discharge in California?
No California page we have sets a discharge rule for yard or perimeter drains, so ask the office that covers your address before the trench is planned. Check the state's landslide zone map for your address as well.
Do I have to call 811 before digging a French drain?
Gov. Code 4216.2 asks for notice at least two working days and no more than 14 calendar days ahead of excavation, except in an emergency. The 24-inch zone either side of a marked line is dug by hand tool.
Will a French drain need a city permit in California?
Under the state code a permit is needed to alter or repair a building, with local requirements varying; no source we have names French drains either way.
Which CSLB class covers drain work?
C-42 covers storm drains and other drain structures with their pipe laying, C-27 grading for landscape systems, and C-12 trenching and grading, and the C-61 list includes D-56 for trenching only. Which one fits is our interpretation.
What does a French drain run in California?
Our estimate is $2,800 to $21,800 per project, with a per-linear-foot range in the table, built from national ranges adjusted for California wages. Ask for the length, the depth and the discharge point in writing.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Construction Laborers (SOC 47-2061), California, mean hourly wage Read Oct 23, 2026.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Construction Laborers (SOC 47-2061), United States, mean hourly wage Read Oct 23, 2026.
- FoundationMatch: how we estimate costs, California (editorial policy) Read Oct 23, 2026.
- SCAG Connect SoCal 2024 Draft PEIR, Section 3.7 Geology and Soils Read Oct 20, 2026. Confirm it with the source itself before relying on it.
- City of Monterey Park: Landscaping on Expansive Soils (CSU Extension 7.236) Read Oct 20, 2026. Confirm it with the source itself before relying on it.
- OpenFEMA API Read Oct 20, 2026.
- CGS Seismic Hazards Program (with EQ Zapp page) Read Oct 20, 2026.
- Government Code 4216.2 (leginfo), with the 2025 California excavation law booklet published by USA North 811 Read Oct 20, 2026.
- USA North 811 home page (county list and FAQ) Read Oct 20, 2026.
- CSLB Licensing Classifications Detail: C-42 Sanitation System Contractor Read Oct 20, 2026.
- CSLB Licensing Classifications Detail: C-12 Earthwork and Paving Contractors Read Oct 20, 2026.
- CSLB: C-61 Limited Specialty classifications list Read Oct 20, 2026.
- B&P Code 7048 (leginfo) Read Oct 20, 2026.
- CSLB Check a License Read Oct 20, 2026.
- CSLB: Do I need a building permit for my project? Read Oct 20, 2026.
- CSLB: What kind of contractor do I need? (with the classification pages and crmp.org ESS page) Read Oct 20, 2026. Confirm it with the source itself before relying on it.