One inch of rain on a 2,000 square foot roof produces about 1,250 gallons of water. Without a proper backyard drainage system, that water has to go somewhere — and in most yards, “somewhere” is the basement, the foundation, or the neighbor’s property line. Poor drainage is the root cause behind 60 percent of basement moisture problems, the majority of foundation cracks under 25 years old, and most failed landscape installations. The good news is that the engineering is simple, the materials are cheap, and most systems are within DIY reach with a rented trencher.
Here is how the major components work and how to size them for your lot.
The Five System Types
Most residential drainage problems are solved by one or a combination of five components.
- French drain: Perforated pipe in gravel-filled trench, collects subsurface water
- Catch basin: Surface grate over an in-ground box, collects surface runoff
- Channel drain (trench drain): Long linear grate, used along patios and driveways
- Dry well: Underground gravel pit or plastic chamber that disperses water into soil
- Swale: Shallow graded channel that redirects surface water
The right system depends on whether your water problem is subsurface (saturated soil, basement seepage) or surface (puddles, sheet flow). Diagnosing correctly saves digging the wrong trench.
Diagnosing the Problem First
Walk the yard during a hard rain. Note where water pools, the direction it sheets, and how long puddles linger after the rain stops. Use a 4-foot level on a straight 2×4 to check yard grade — the recommended minimum slope away from the foundation is 6 inches over the first 10 feet, or about 5 percent grade. Anything less than 2 percent grade does not drain reliably even in well-prepared soil.
Check downspout outlets. If they discharge within 6 feet of the foundation, that water re-enters the soil right where it can damage the basement. Extending downspouts 8 to 10 feet with corrugated black pipe ($14 to $24 per kit at Home Depot) solves a surprising percentage of foundation moisture issues for under $100.
French Drain Installation
A French drain is the workhorse of residential drainage. The standard build is a 12 to 18 inch deep trench, 6 to 8 inches wide, lined with non-woven landscape fabric (Mirafi 140N or similar), filled with #57 washed gravel around a 4-inch perforated corrugated pipe.
- Rent a trencher from Home Depot ($85 to $125 per day) or a rotary tiller for shallow runs
- Trench 12 to 18 inches deep, sloping 1 to 2 percent toward the discharge point
- Line the trench with non-woven landscape fabric, leaving 12 inches of overhang on each side
- Add 2 inches of #57 washed gravel at the bottom
- Lay perforated pipe with holes facing down (counterintuitive but correct — water enters from below as the table rises)
- Cover with 4 to 6 inches of gravel, fold the fabric overlap across the top
- Backfill with topsoil or sod cap
Materials cost: $5.50 to $9 per linear foot. Professional install runs $25 to $55 per linear foot. A typical 50-foot French drain DIY job lands at $300 to $450 in materials and one weekend of labor.
Catch Basins and Channel Drains
Catch basins handle concentrated surface water — the puddle that always forms at the low corner of the patio. NDS 9-inch and 12-inch catch basins are the standard residential sizes, running $18 to $42 per unit plus $8 to $14 for the grate. Install them flush with grade, connected to 4-inch solid PVC pipe sloped at 1 to 2 percent toward an outlet (storm drain, dry well, or daylight discharge).
Channel drains (trench drains) are continuous linear grates 8 to 24 feet long. NDS Spee-D Channel and EZflow channel drains are the residential standard at $32 to $58 per 10-foot section. Use them along garage door thresholds, pool decks, and patio edges where sheet flow needs interception.
Dry Wells for Yards Without Daylight Outlets
Many lots cannot discharge drainage to a storm sewer or daylight on the property. A dry well solves this by creating an underground holding area where water slowly percolates into the soil. The simple version is a 4-by-4-foot pit, 4 feet deep, filled with #57 gravel and wrapped in landscape fabric — capacity around 380 gallons.
The premium version uses NDS Flo-Well or EZflow dry well chambers ($85 to $185 per chamber), which give 50 to 75 gallons of capacity per unit in a smaller footprint and can be daisy-chained for larger volumes. Sizing rule: 1 chamber per 500 sq ft of contributing impervious area in well-drained soil, doubled in clay soils.
Pricing the Full Build
Costs vary widely depending on lot size, soil type, and access for equipment.
- Downspout extensions: $80 to $200 total
- Single catch basin install: $250 to $500
- 50-foot French drain DIY: $300 to $500 materials
- 50-foot French drain professional: $1,250 to $2,750
- Channel drain at garage entry: $400 to $900 installed
- Dry well system: $600 to $2,200 depending on size
- Whole-yard drainage redesign: $4,500 to $12,000
Sump Pumps and Battery Backup
If your drainage system terminates in a sump pit (common in basements and low yards), the pump matters more than the drains feeding it. Zoeller M53, Liberty 257, and Wayne CDU800 are the residential workhorses at $180 to $350. Pair them with a battery backup like the Wayne ESP25 ($375) — sump pump failures during power outages account for a large share of finished basement flooding claims.
Sizing: most homes need a 1/3 to 1/2 HP pump rated for at least 35 gallons per minute at 10 feet of vertical lift. Confirm the discharge pipe is at least 1-1/2 inch diameter and has a check valve to prevent backflow.
Maintenance That Keeps the System Working
Drainage systems fail mostly from clogging. Twice a year, clear leaves and debris from catch basin grates and channel drain inlets. Once a year, snake the discharge line with a 25-foot drain snake (DeWalt DCD800 cordless or a manual Ridgid K-3) to clear sediment buildup. After major storms, walk the system and verify water flows from inlets to the discharge point without backing up. Catching a clog early is the difference between a $30 cleanout and a $1,500 repair.
