Pickleball court stormwater and drainage in St. Louis

Last updated: October 10, 2026

Yes — a pickleball court is impervious surface. Kirkwood's stormwater guidance lists sport courts and tennis courts by name, and a 30 × 60-foot court adds 1,800 square feet of it. Whether that triggers a requirement depends on where you live: MSD's water-quality rules start at one acre of disturbance, so a backyard court rarely reaches them, but Kirkwood requires a drywell or similar practice at 1,000 square feet of new impervious area, and St. Louis County's grading exemptions come with conditions about your neighbors' drainage. Separate from the rules, every court needs a base and slope that move water off the court and somewhere it can go.

Why drainage decides how long a court lasts

Water is the enemy of a court in three ways. Standing water on the surface grows algae and mildew and makes play slippery. Water in the base softens it and lets the slab settle unevenly. And water that freezes — in cracks, at the edges, in a soggy base — lifts and breaks things. St. Louis's wettest months on the 1991–2020 normals are May (4.82 inches) and April (4.73 inches), with 41.7 inches a year; all of it has to go somewhere.

Good court drainage has three parts:

1. A drained base. Compacted crushed stone over a prepared subgrade, so water that gets under the slab moves through rather than sitting in clay. The slab guide explains why that matters so much on St. Louis clay.
2. Surface slope. Courts slope in one plane — typically across the width, from one sideline to the other — so water sheets off without crossing the play in odd directions. A court that's crowned or sloped two ways plays strangely.
3. Somewhere for the water to go. A swale, an edge drain, a drywell or a rain garden. Not the neighbor's yard.

Does MSD regulate a backyard court?

Usually not directly. The Metropolitan St. Louis Sewer District requires post-construction stormwater water-quality practices on projects that disturb one acre or more, or smaller sites that are part of a larger common plan of development. A backyard court disturbs a few thousand square feet.

MSD does review "all public or private sewerage and drainage works" that are built or altered, including changes to site drainage or a floodplain. If your court project involves connecting a drain to a storm sewer or altering a drainage channel, that's MSD's business. MSD's structural practices are designed to capture and treat the first 1.14 inches of rainfall, the 90th-percentile daily storm.

MSD's Rules and Regulations are being updated: plans first submitted on or after January 1, 2027 fall under the new edition. We'll check the edition that applies when your project is submitted.

St. Louis County's grading rules

Unincorporated St. Louis County's Land Disturbance Code (Chapter 1114, also adopted by a number of municipalities) requires a permit for land disturbance unless an exemption applies. Two exemptions matter for a court:

• Small disturbances: work that moves less than 30 cubic yards of earth and disturbs less than 2,000 square feet, for improvement of the property. Both limits apply. A 34 × 64 pad disturbs more than 2,000 square feet; a 30 × 60 pad with its working room usually does too.
• Accessory structures for one- and two-family homes: land disturbance associated with additions and accessory structures.

Both exemptions come with conditions. They don't apply if the work cuts or fills at a property line, permanently diverts drainage, deposits silt or mud on another property, erodes or damages a neighbor's land, blocks a swale, or works in a floodplain or creek channel. A court that sheds its water onto the house next door can lose the exemption it would otherwise have.

St. Charles County's unincorporated code is different: a land disturbance permit is required at 5,000 square feet or more of disturbance, with limited exemptions.

Kirkwood: the city with a court-sized trigger

Kirkwood has the most specific rule for a homeowner building a court. Under its infill stormwater ordinance, a project that creates 1,000 square feet or more of net additional impervious area, or brings total impervious area to 25% or more of the lot, must provide stormwater mitigation sized to capture the first 1.14 inches of runoff. Kirkwood's guidance lists "sport courts, tennis courts" as impervious and names "sport court" among the project types that can trigger it.

A 30 × 60 court is 1,800 square feet. A 34 × 64 court is 2,176. Either one trips the trigger on its own.

Pending change: Kirkwood has proposed lowering the threshold from 1,000 to 500 square feet, capping single-family impervious coverage at 55%, and requiring a grading permit for flatwork over 100 square feet. A town hall was held in June 2026 and the Webster-Kirkwood Times reported in August 2026 that a final draft was headed to council. As of that August reporting it had not been adopted. We'll check the current rule before we submit anything in Kirkwood.

Kirkwood's drywell specification

Kirkwood publishes residential green-practice specs. For aggregate drywells, its guidance includes:

• at least 10 feet from building foundations, basements, retaining walls, in-ground pools and property lines;
• spacing between drywells of at least 30 feet or twice the depth of the deepest one, whichever is greater;
• aggregate depth between 24 and 72 inches, filled with washed ASTM No. 57 stone;
• the bottom below the frost line — Kirkwood cites St. Louis County's 30-inch frost depth — and at least 2 feet above groundwater or bedrock.

Those setbacks matter on a typical Kirkwood lot. A drywell has to fit 10 feet from the property line and 10 feet from the house, outside the court footprint, with room for the pipe to reach it. We plan the drywell location at the same time as the court.

Rain gardens and modified French drains are among Kirkwood's other accepted practices; which one fits depends on your soil and space.

Floodplains: Chesterfield Valley and elsewhere

If your property is in a FEMA special flood hazard area or a locally regulated floodplain, expect a floodplain development permit before any grading or building permit. Chesterfield, for example, requires one in its special flood hazard areas and supplemental protection areas, at no fee. The Chesterfield Valley itself sits behind the Monarch-Chesterfield levee. A court is low and doesn't block flow much, but fill does, and floodplain rules care about fill.

How we drain a court on clay

On a St. Louis site, our court crew:

• Reads the lot first. Where does water go now, after a hard rain? Photos after a storm are the best thing you can send us.
• Strips and proof-rolls the subgrade. Soft spots get dug out and replaced.
• Builds a compacted stone base at a depth set for the soil, so water under the slab has a path.
• Slopes the court in one plane to the low side, away from the house and the neighbors.
• Catches the runoff in a swale, edge drain, drywell or rain garden, sized to the court and to any city requirement.
• Keeps downspouts and yard water off the court. A court shouldn't be the drainage path for the rest of the yard.

Sloped lots need extra thought. Cutting a flat pad into a hillside creates a high side that collects water from above; a swale or curtain drain along the uphill edge keeps it off the court.

Drywell, rain garden or swale?

On tight clay, any practice that depends on soaking water into the ground works slowly; that's why Kirkwood's spec ties drywell size to the area it drains. Grading and stormwater permits sometimes come with the court; the permits guide lists what each city requires.

What it adds to the cost

A swale is often just grading. An edge drain is trenching, pipe and stone. A drywell is excavation, stone, fabric and pipe, sized by the city's formula where one applies. These appear as separate lines on our quote. See the cost guide.

Related guides

• Why base and slab choice depend on the same clay: post-tension vs asphalt vs concrete
• Which other permits apply by city: pickleball court permits in St. Louis
• Keeping a court draining for years: maintenance in freeze-thaw country

Frequently asked questions

Does a pickleball court count as impervious surface? Yes. Kirkwood's guidance lists sport and tennis courts by name, and most stormwater rules treat paved and coated surfaces as impervious.

Do I need a drywell for a court? In Kirkwood, almost certainly — a court exceeds the 1,000 square foot trigger. Elsewhere, it depends on the city and the site.

Can the court drain onto my lawn? Often, yes, if the lawn can take it and the water doesn't end up on a neighbor's property. Clay lawns soak up little in a hard storm.

What about permeable courts? Modular tiles drain through to the slab, but the slab underneath is still impervious. Some cities treat that the same as any court.

Get a quote

Send us photos of your yard after a rain and your city. We'll plan the court and its drainage together. See backyard pickleball courts, or get a quote.