Signs your French drain has failed
- The ground above the drain stays soggy after storms.
- Puddles are back where the drain used to clear them.
- The outlet stays dry during heavy rain, or only trickles.
- Water bubbles up from a cleanout or a low point along the line.
- Sinkholes or a sunken strip along the trench.
Common causes
| Cause | What happens | Typical on |
|---|---|---|
| Silted rock | Fine soil washes into the rock and the pipe; water can no longer reach the pipe | Drains built without filter fabric |
| Crushed or flat pipe | Thin pipe collapses, or the line sags and holds water | Shallow lines under driveways or heavy equipment |
| Roots | Tree roots follow the moisture into the pipe | Lines near oaks and other large trees |
| Buried or blocked outlet | Landscaping, soil or debris covers the outlet; water has nowhere to go | Older lots that have been re-landscaped |
| No outlet at all | The drain was built to a dead end and fills up | DIY or very old installs |
Many homes here date from the 1960s and 1970s (median year built 1960 in Lafayette and Orinda, 1974 in Walnut Creek per the U.S. Census), so some drains are decades old and predate modern filter fabrics.
Diagnosis first
Ask for a camera inspection through a cleanout or the outlet before agreeing to dig. It shows where the pipe is blocked, crushed or full of roots and how far along the line the problem runs. If there are no cleanouts, the contractor may open the line at one or two points.
Repair options
| Option | When it fits |
|---|---|
| Jet or snake the pipe | Silt or small roots in the pipe; rock still drains |
| Open and clear the outlet | Outlet buried, crushed or blocked |
| Replace a section | One crushed or sagging section; roots at one spot |
| Add cleanouts | Any repair, so the line can be maintained |
| Full replacement | Rock silted along most of the run, no fabric, no consistent fall, or no workable outlet |
When replacement makes sense
If the rock is clogged along most of the line, cleaning the pipe only buys a season. Replacement rebuilds the trench with fabric, fresh rock, new pipe with consistent fall, cleanouts and a real outlet. The installation page explains what a new system should include.
Cost
Cleaning runs about $80–$500+ (HomeGuide); section repairs and full replacement are priced by linear foot like new work. See the cost guide.
Questions homeowners ask
How do I know if my French drain is clogged?
The ground over the line stays wet, water pools where it used to drain, or the outlet stays dry during a heavy rain when it used to run. A camera inspection through a cleanout confirms it.
Can a French drain be cleaned out?
Often the pipe can: water jetting or snaking through a cleanout clears silt and small roots. Rock that is packed with fine soil can't be cleaned in place and has to be dug out and replaced. Cleaning typically costs $80–$500+ (HomeGuide).
Should I repair or replace my French drain?
Repair when the problem is local (one crushed section, a buried outlet, roots at one spot). Replace when the rock is silted along most of the run, there was never fabric, or the pipe has no consistent fall.