Trench Drain Cost Estimator
A trench drain - also called a channel drain - is a long, narrow surface drain with a grate that catches sheet water across a line, instead of at a single point like a floor drain. It is the go-to fix in Florida for pool decks, lanais, garages, and driveways where heavy rain sheets across flat concrete. The channel is set into the slab and pitched to an outlet. The big cost drivers are whether it goes in before a new pour (easy) or has to be saw-cut into existing concrete (much more work), the run length, and where the water can actually go - which in Florida's flat lots and high water table sometimes means a dry well or a pump rather than a simple gravity outfall.
These get mixed up. A trench (channel) drain is a surface drain: a linear channel with a grate, flush with the concrete, that catches runoff sheeting across a deck or driveway. A french drain is the opposite - a buried, perforated pipe in gravel that collects water below grade. A floor drain catches water at a single low point.
Why It Matters
Use a trench drain where water runs across a wide hard surface - pool decks, garage aprons, thresholds. Use a french drain for subsurface/yard water and a point floor drain for a contained low spot. Picking the wrong one is the most common drainage mistake.
Florida's flat lots, big slab areas, and intense rain make channel drains common across pool decks and lanais (keep water off the deck and out of the pool), garage and driveway aprons (stop water running into the garage), and door thresholds where sheet water threatens to come inside.
Why It Works Here
A line drain across the low edge of a slab intercepts a whole sheet of water at once, which a single point drain cannot do on a broad flat surface. That is exactly the problem most FL hardscapes have.
The single biggest cost factor is timing. Setting the channel in the forms before concrete is poured is clean and relatively cheap - the slab is built around it at the right pitch. Retrofitting into an existing slab means saw-cutting, demolishing a strip of concrete, setting the channel, and patching - far more labor and a visible patch line.
Plan It In
If you are pouring a new deck, driveway, or garage floor, design the trench drain in now. Retrofits are worth it when an existing surface already floods, but expect the higher number.
Water only leaves if it has somewhere to go. The channel is pitched to an outlet, then the outlet has to daylight, tie into a storm system, reach a dry well, or be pumped.
The FL Challenge
On flat lots there may be little fall to a daylight point, and a high water table can limit how well a dry well drains in the wet season. Sometimes the only reliable answer is a sump basin and pump at the low end. This is why two identical-looking jobs can price very differently - it is all about where the water goes.
Channels come pre-sloped (built-in fall so a flat slab still drains) or neutral (you build the pitch into the slab). Pre-sloped is easier to get right on dead-flat Florida hardscapes but costs a bit more.
Grates
Grate choice matters: heel-proof / ADA patterns for walking surfaces, load-rated grates for driveways and vehicle traffic, and decorative or brass grates for pool decks. The grate load rating must match the traffic.
Width & Flow
Channel width and grate open area should match the expected flow - undersized channels overflow in a hard FL downpour.
Best Time: New Pour
Setting the channel before the concrete pour - pitched to a planned outfall - is by far the simplest and cheapest path.
Typical Retrofit
1. Mark the line and confirm where the water will discharge. 2. Saw-cut and remove a strip of concrete. 3. Set the channel to pitch and secure it. 4. Run the outlet to daylight, a storm tie-in, a dry well, or a pump basin. 5. Pour/patch the concrete around the channel. 6. Set the grate and test with a hose.
FL Gotchas
No real outfall (water with nowhere to go), too little slope, an undersized channel, a grate not rated for the traffic, and ignoring stormwater tie-in rules.
A channel drain only works if it stays clear. Florida throws leaves, sand, grass clippings, and pool debris at it year-round.
Routine Care
Lift the grate and clear the channel and any catch basin/sediment bucket; flush it with a hose. Check that the outfall, dry well, or pump is still moving water - especially before hurricane season and the summer rains.
Warning Signs
Standing water in the channel, water backing onto the deck or into the garage, or a sump pump running constantly all signal a clog or a failing outfall that needs attention.
The channel and grate are a modest part of it; the concrete work and the outfall drive the price. These are planning estimates for the work plus professional labor in the FL market.
Install Situation
Setting it in a new pour is the low end; a saw-cut retrofit into existing concrete is the high end.
Length & Outfall
Longer runs add channel and labor, and a tough outfall - a storm tie-in, a dry well, or a pump for a low spot with no gravity drainage - adds the most.
Grates & Extras
Premium heel-proof or decorative grates and accessories add. Use the calculator to combine location, install situation, length, and add-ons.
FL Permit Requirements
- Clearing and flushing an existing channel drain
- Replacing a grate on an existing channel
- Surface-only channel set in a new private hardscape pour (verify locally)
- Saw-cutting an existing slab to retrofit a channel drain
- Tying the outfall into a storm/stormwater system
- Installing a sump basin and pump for a low spot
- Drainage work that alters site stormwater / grading
FL County Permit Fee Reference
Clearing a channel or swapping a grate is usually minor. Saw-cutting concrete to retrofit a trench drain, tying into a storm/stormwater system, or adding a pump is regulated work that is often permitted, and stormwater tie-ins or site-grading changes can trigger additional review. Fees and timelines are approximate — verify with your local building department / AHJ before starting work.
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FL Code References
Who Can Pull a Permit in FL?
Cutting concrete to set a trench drain, tying its outfall into a storm or stormwater system, and installing a sump and pump are regulated work that often requires a permit, and changes to site drainage or grading may need additional stormwater review. Channel slope and outfall, grate load rating, any storm-system connection, and pump wiring follow the adopted code, any local amendments, and stormwater rules, and the work is generally permitted. Clearing a channel or swapping a grate is usually minor. Per FL Statute 489.105, regulated plumbing and related construction work is performed by the appropriate licensed contractor.
Verify any contractor's license at myfloridalicense.com and confirm requirements with your local building department before work begins.
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Licensed FL Contractor - Channel Drains, Outfalls & Pumps
We install trench (channel) drains for pool decks, lanais, garages, and driveways — set before the pour or saw-cut into existing concrete — pitched to a real outfall, with the storm tie-in, dry well, or sump pump that Florida's flat lots and high water table often require, and grates rated for the traffic.