Standing water in a yard is a symptom, not a diagnosis, and the fix depends entirely on the cause. Regrading a lawn that is actually suffering from four downspouts dumping 2,000 gallons at the foundation will not help. A French drain installed in dense clay with nowhere to daylight is just an expensive underground puddle. Spend an hour diagnosing before you spend a weekend digging. Most single-cause problems are a one-to-two-day DIY project running $300–$1,500 in materials; anything involving the foundation or a neighbor’s runoff deserves professional eyes.
Tools & Materials
- Washed #57 stone for any drain trench or dry well
- Non-woven filter fabric, wide enough to wrap the trench
- 4 in perforated drain pipe, plus solid pipe for downspout runs
- Topsoil for regrading and swale shaping
- Line level or laser level, stakes, mason’s string, tape measure
- Trenching shovel, mattock, or a rented trencher for long runs
- Wheelbarrow, landscape rake, hand tamper
Once you know which fix you need, size the stone with the French drain calculator or the drainage gravel calculator. For a rough sanity check: 1 yd³ of stone fills about 27 linear feet of a 12 in wide by 12 in deep trench, less the pipe volume.
Step 1: Diagnose the Actual Cause
There are three common causes and they demand different fixes. Work through them in this order.
Roof and Hardscape Runoff
Check this first because it is the cheapest to fix and the most commonly responsible. A 1,500 sq ft roof sheds roughly 900 gallons in a 1 in rainfall, and if that lands at four downspout splash blocks it will overwhelm any lawn. Go outside during actual rain and watch. If the wet area sits within 15 ft of a downspout, a driveway edge, or a patio that drains toward the lawn, you have a concentrated-water problem, not a soil problem.
Negative or Flat Grade
Run a string line from the foundation outward with a line level. Ground should fall at least 6 in over the first 10 ft away from the house — a 5% slope. Across open lawn, 1–2% is enough to move surface water. If the string shows flat ground or, worse, ground rising away from the house so water is trapped against it, the water has nowhere to go by gravity and no subsurface drain will fully compensate.
Soil That Will Not Absorb
Dig a hole 12 in deep and 12 in wide, fill it with water, let it drain completely, then fill it again and time it. Draining under 1 in per hour on the second fill means poorly draining soil — usually heavy clay or a compacted layer left by construction equipment. This is the case where subsurface drainage genuinely earns its cost, because surface grading alone just moves the puddle.
Pro tip: Photograph the yard mid-storm and again two hours after it stops. Water that is gone within two hours is a soil-absorption issue you can often live with; water still sitting the next day is a genuine drainage failure that needs an engineered path out.
Step 2: Choose the Right Fix
| Solution | Best for | Requires | Typical DIY cost |
|---|---|---|---|
| Downspout extensions | Wet spots near the house | Somewhere downhill to discharge | $20–$150 |
| Regrading | Flat or negative grade near foundation | Topsoil, a rake, and a slope to work with | $200–$800 |
| Swale | Sheet flow crossing a lawn | Room for a shallow channel and an outlet | $300–$900 |
| French drain | Saturated soil, springs, wet slopes | 1% fall to a daylight outlet | $600–$1,500 |
| Dry well | Concentrated water with no outlet | Soil that percolates below the well | $300–$900 |
The decision hinges on one question: do you have somewhere lower to send the water? If yes, a French drain or swale carries it there. If no — a flat lot, no street ditch, no legal discharge point — you must store and infiltrate it locally with a dry well, and that only works if the soil below the well actually percolates. Never discharge onto a neighbor’s property; in most jurisdictions that is your liability.
Step 3: Do the Work
- Extend every downspout at least 10 ft from the foundation. Do this before anything else, because it is cheap and it often solves the whole problem. Use solid (not perforated) pipe buried just below grade, sloped a minimum of 1% — 1 in per 8 ft — to a pop-up emitter or a daylighted end downhill. Splash blocks alone do not move enough water away from the house to matter.
- Re-establish positive grade around the foundation. Add topsoil against the house and rake it out to fall 6 in over the first 10 ft. Keep the finished soil at least 6 in below siding, brick weep holes, and any wood. Tamp lightly and reseed; loose fill settles and you will need a top-up pass the following season.
- Cut a swale to intercept sheet flow across the lawn. A swale is a broad, shallow, grassed channel — roughly 8–12 in deep with gently sloped sides you can mow across — running perpendicular to the flow and pitched at least 1% toward the outlet. Shape it with topsoil rather than digging a trench, and sod or seed it heavily so it never scours.
- Install a French drain where the soil itself is saturated. Dig a trench at least 12 in deep, sloped 1% minimum toward a daylight outlet. Line it with non-woven filter fabric, add 2–3 in of washed #57 stone, lay 4 in perforated pipe with the holes facing DOWN, backfill with more #57 to within a few inches of grade, then fold the fabric over the top to close the burrito. Holes down is not a typo — water rises into the pipe from the surrounding stone. Full detail is in our French drain installation guide.
- Build a dry well only where the water has no outlet. Excavate a pit — typically 3–4 ft across and 3–4 ft deep, sized to the roof area feeding it — well away from the foundation and any septic field. Wrap it in filter fabric, fill with washed #57 stone or set a perforated dry well chamber in stone, and pipe the downspout into it. Size the stone with the drainage gravel calculator.
- Give any daylight outlet a stone apron. Where a drain or swale discharges, place a few square feet of larger crushed stone to dissipate flow energy. Without it the outlet erodes a gully and eventually undercuts the pipe.
- Fix the surface last, once the water is under control. Regrade low spots, add topsoil, and reseed. Doing turf repair before the drainage work is finished just means doing it twice.
Critical: Never route surface drainage or downspouts into a sanitary sewer cleanout, and never tie a French drain into a foundation footing drain unless you have confirmed the footing drain has capacity and a working outlet. Overloading a footing drain pushes water into the basement it was built to protect.
Sizing the Stone and the Trench
Two dimensions drive the material order. Trench width is normally 12 in — wide enough to bed a 4 in pipe with stone on both sides, narrow enough to dig by hand. Depth starts at 12 in at the high end of the run and increases as you carry the 1% fall toward the outlet, so a 60 ft drain finishing at 1% is roughly 12 in deep at the head and 20 in deep at the tail. That deepening is exactly what people forget when they order stone, and it is why so many jobs run short in the last 15 feet.
Use washed #57 stone and nothing else. Crusher run, screenings, and pit-run gravel all contain fines, and fines are what turn a drain into a plug. Non-woven filter fabric — not the woven fabric sold for weed control — is what lets water pass while holding silt out; the two products look similar on the shelf and perform completely differently underground. Our guide to landscape fabric under gravel explains which is which.
Troubleshooting
The drain works for a year, then stops. Almost always silt. Either filter fabric was omitted, the wrong fabric was used, or unwashed stone with fines in it was installed. Non-woven fabric fully wrapping washed stone is the only configuration that stays clear long term.
Water backs up out of the pipe. Check the outlet first — blocked by soil, mulch, or a rodent nest is the usual answer. If the outlet is clear, the slope is probably insufficient; anything under 1% will not self-clear and sediment accumulates until it plugs.
The yard is still soggy after a French drain. You likely fixed subsurface water when the real problem was surface water, or vice versa. Repeat the diagnosis. A drain 20 ft from the wet spot in clay soil barely influences it — water does not travel sideways through clay.
The dry well overflows in heavy rain. It is undersized, or the soil below it does not percolate. Do a perc test at the bottom of the pit depth, not at the surface. If that layer will not take water, a dry well is the wrong tool and you need a piped route to a real outlet.
Bottom Line
Diagnose first: watch it rain, run a string line for grade, and do a percolation test. Fix downspouts before you dig anything. Regrade to 6 in of fall in the first 10 ft from the house. Use a swale for surface flow, a French drain for saturated soil with an outlet available, and a dry well only when there is nowhere to send water and the subsoil will take it. Every subsurface solution needs washed #57 stone, non-woven fabric fully wrapping it, and at least 1% of fall. Size the stone with the French drain calculator or the #57 stone calculator. If the wet area is decorative rather than structural, a dry creek bed handles the same runoff and looks intentional doing it.
