A drainage system that works is invisible. Rain comes, water goes somewhere else, and you never think about it. A drainage system that has failed announces itself — usually about eighteen months after somebody installed it, usually during the first serious fall downpour, and usually in the exact spot it was supposed to fix.
If you paid for drainage work in the last few years and the water is back, here's how to tell what actually went wrong.
The obvious one, and the most common. If puddles are sitting in the same place they sat before the work was done, the system either never had enough fall to move water or it has silted shut. Chattanooga's clay-heavy soil is unforgiving here — a French drain needs consistent pitch, and a trench that dips even slightly in the middle becomes a buried bathtub.
The tell: water that stands for more than 24 hours after rain stops. Healthy drainage clears a yard within a few hours.
Go find where your drain daylights — usually a pop-up emitter or a pipe end at a slope or ditch line. Walk out there during or just after a heavy rain. A working system pushes real volume out of that pipe. A trickle, or nothing, while your yard is flooding upstream, means the line is blocked between the inlet and the outlet.
Sometimes the outlet itself is the problem: a pop-up emitter buried under three years of mulch and leaf litter, or a pipe end that got graded over when somebody put in a new bed. That's the cheap version of this failure — often a $200 to $400 fix.
Walk the path of the buried pipe. If the ground above it is consistently softer than the surrounding yard, or if grass there is noticeably greener and thicker, water is sitting in the trench instead of moving through it. That points to a collapsed pipe, a crushed section from vehicle traffic, or gravel that has packed solid with silt.
This is the failure mode that comes from skipping filter fabric. Without fabric wrapping the gravel, fine clay migrates in and fills every void. The trench turns into a mud column, and the pipe inside it stops mattering. There's no cleaning your way out of it — the trench gets rebuilt.
A drain that has partially failed doesn't stop moving water; it moves it to the wrong place. If you've got a wet crawl space, a damp foundation corner, or a soggy patch in a neighbor's yard that never used to be there, the system may be discharging underground where it shouldn't. Downspout lines tied into a failed yard drain are a frequent culprit — all that roof volume has to go somewhere, and if the main line is plugged it backs up and finds the path of least resistance, which is often straight down along your footing.
This is the expensive failure, because it's the one that does structural damage while it works on you quietly.
Surface evidence that water is sheeting across the yard rather than entering the system. Look for rills cut into bare soil, mulch stacked against a downhill edge, or the drain's own gravel showing through where topsoil washed off. Usually that means surface inlets are too few, too high, or clogged with debris — a grate sitting an inch above grade collects nothing.
Costs vary with access, length, and how much of the original work has to come out, but general ranges look like this:
The honest version: if the original trench was built without filter fabric or without adequate fall, repairs are throwing money at a design problem. We'd rather tell you that on the first visit than sell you two rounds of jetting.
A proper assessment means walking the yard during or right after rain, locating and inspecting the outlet, checking grade with a level across the trench line, and in some cases running a camera through the pipe. That tells us whether you're looking at a $300 morning or a rebuild — and either answer is better than guessing.
If your system is failing, start with a look at how a French drain should be built, or see our approach to whole-yard drainage when the problem is bigger than one trench. Free on-site assessments: call (423) 497-3591.
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Call (423) 497-3591