Residential Drainage Design in Palm Beach County: How to Stop Yard Flooding
September 2, 2026
Residential drainage design is the plan for where rainwater goes once it hits your roof, driveway, pool deck, and lawn. In Palm Beach County that plan has to deal with flat lots, a high water table, and 60-plus inches of rain a year, and it usually has to keep every drop on your own property. This guide explains how a drainage contractor approaches a flooding yard, the difference between a French drain and an exfiltration trench, and what to expect from a residential or commercial drainage design in West Palm Beach, Palm Beach Gardens, Jupiter, Royal Palm Beach, Loxahatchee, and Boca Raton.
Why Yards Flood in South Florida
Most drainage problems here come down to three things. The ground is nearly flat, so water has nowhere to run. The water table sits a few feet below grade and rises during the wet season, so the soil is already full when the heavy rain arrives. And every new roof, paver driveway, and pool deck replaces sand that used to soak up water with a hard surface that sheds it. The result is standing water in the low corner of the yard, a side yard that never dries out, or a patio that floods every afternoon in August.
Older neighborhoods have a second issue: the original grading has settled, been buried under decades of mulch and sod, or been undone by a neighbor's addition. Water that once ran to the swale now runs toward the house.
How a Drainage Design Starts
Good drainage design starts with elevations, not products. A survey or a contractor with a laser level establishes the finished floor, the low spots, the crown of the road, and the elevation of any existing drain or swale. From there the design answers one question for every square foot of the site: where does this water go, and does it get there by gravity?
On permitted projects in Palm Beach County, an engineer produces the site drainage plan. Municipal stormwater codes, including the Town of Palm Beach's Article III stormwater management rules, generally require runoff from new impervious area to be retained on site rather than discharged to the street or a neighbor. The engineer sizes the storage, sets pipe inverts, and fixes the top-of-exfil elevation. The contractor builds it exactly to those numbers, because a pipe set a few inches high or an exfil trench a foot too shallow will not drain.
Grading and Drainage Work Together
Grading and drainage are one system. Surface grading moves water across the lawn toward a collection point. Swales along the property line carry it to the front or rear. When there is enough fall, a regrade alone fixes many yard flooding problems and costs far less than pipe. When there is not enough fall, which is common on Palm Beach lots, the water has to go underground.
French Drains vs. Exfiltration Trenches
People search for French drains in West Palm Beach more than any other drainage product, and most of the time what they actually need is an exfiltration trench. The two look similar but work in opposite directions.
- French drain — a gravel-filled trench with perforated pipe that collects water from the surrounding soil and carries it to an outlet. It relieves a wet area but needs somewhere lower to discharge.
- Exfiltration trench — a rock-filled trench with perforated pipe that receives piped stormwater from roof drains and area drains and lets it soak back into the ground. It is the on-site storage the code requires, and it works without an outlet.
Because most Palm Beach County lots have no legal outlet and no fall, the exfiltration trench is the backbone of nearly every residential and commercial drainage design we build. The engineer sizes it by the volume of runoff the site must hold; the contractor's job is to hit the elevations, use the specified rock, wrap it in filter fabric, and keep fines out of it during construction.
The Components of a Residential Drainage System
How the pieces of a residential drainage design connect: surface drains and downspouts feed an underground exfiltration trench that soaks stormwater back into the ground above the water table.
Area Drains and Catch Basins
Area drains sit at the low points of lawns and planting beds. Catch basins do the same job with a sump so sediment settles out and can be cleaned. Both connect by solid pipe to the exfiltration system.
Roof Downspouts
A roof concentrates thousands of gallons in a single storm. Downspouts are piped underground directly to the exfil rather than dumped at the foundation.
Trench Drains, Slot Drains, and Deck Drains
Driveways, pool decks, and patios use linear trench drains or narrow stainless slot drains that intercept sheet flow across a hard surface before it reaches a door or the pool.
Bubble-Ups and Overflows
An overflow or bubble-up gives the system a safe place to surface if a storm exceeds the design capacity, so excess water appears in a planned spot in the lawn instead of the garage.
Storm Lift Stations
On low waterfront lots where gravity will not work, a small storm lift station pumps collected water up to the exfil or to a permitted outfall.
What a Drainage Contractor Actually Does
Searches for storm water drainage contractors near me usually mean someone has a design, or a flooding problem, and needs it built. On a typical residential drainage installation, SMC Contracting handles:
- Utility locates and permit coordination with the municipality.
- Excavation of the exfiltration trench and drain runs, with dewatering when the water table is above the trench bottom.
- Setting pipe, basins, and drains to the engineered elevations.
- Placing washed rock and filter fabric, then backfilling and compacting in lifts.
- Final grading and swales so surface water reaches the drains.
- Restoring sod, pavers, and hardscape.
For existing systems that have stopped working, we start with a camera inspection and vac and jet cleaning. A surprising number of "failed" exfil trenches are simply full of sand from a construction phase that never had erosion control.
Commercial Drainage Design
Commercial drainage design follows the same physics with larger numbers: bigger roofs, parking lots, and stricter water-quality requirements. Projects typically include pre-treatment structures, baffled collection basins, larger exfiltration fields, and custom concrete drain structures. SMC builds these for commercial sites in West Palm Beach, Palm Beach Gardens, and across Palm Beach and Martin counties.
Frequently Asked Questions
What is the difference between a French drain and an exfiltration trench?
A French drain is a gravel trench with perforated pipe that collects groundwater or surface water and carries it somewhere else. An exfiltration trench is the reverse: piped stormwater from roof drains and area drains is delivered into a rock-filled trench and allowed to soak back into the ground on site. In Palm Beach County, exfiltration is the standard engineered solution because most municipalities require runoff to be retained on the property.
Do I need an engineer for a residential drainage design?
For new construction, additions, and most permitted hardscape work in Palm Beach County, yes. The engineer sizes the exfiltration system and sets pipe elevations to meet the local stormwater code. For smaller yard drainage fixes such as a soggy side yard or a flooding patio, an experienced drainage contractor can often design and install the solution directly.
Why does my yard flood in Palm Beach County?
South Florida is flat, receives 60 or more inches of rain a year, and has a high water table that rises in the wet season. Water that used to soak in is now displaced by roofs, driveways, and pool decks, and it collects in the lowest spot. Fixing it means either regrading so water flows to a drain, or adding capacity underground so it has somewhere to go.
What does a drainage contractor do?
A drainage contractor installs the system: excavation, exfiltration trenches, catch basins, area drains, trench and slot drains, downspout piping, swales, and final grading. SMC Contracting also handles dewatering, backfill and compaction, permitting coordination, and surface restoration so the property is put back the way it was.
Drainage Design and Installation in Palm Beach County
SMC Contracting has installed drainage and stormwater systems in Palm Beach County since 1974. As a licensed general contractor (CGC1512903), we handle the full scope from excavation and exfiltration to grading and restoration for homeowners, builders, and commercial properties in West Palm Beach, the Town of Palm Beach, Palm Beach Gardens, Jupiter, Royal Palm Beach, Loxahatchee, and Boca Raton. If your yard, driveway, or site floods, contact us for an assessment.
