Storm Drain vs. Catch Basin

People use "storm drain" and "catch basin" like they mean the same thing, and contractors don't always help. They're related, but they're not the same, and the difference matters when you're figuring out what your yard actually needs.

The short version

• A catch basin is one specific part: a box or bowl set in the ground with a grate on top that catches surface water, lets debris settle to the bottom, and sends the water out through a pipe.
• A storm drain is the whole system for getting rainwater away: the inlets, the pipes, and wherever it ends up. The big one is the city's network under the street, but people also call their own yard's system a storm drain.

So a catch basin is usually one piece of a storm drain system, the part where water gets in.

What a catch basin does

Rain runs across your patio, lawn, or driveway and hits the grate at the low point. Inside the basin there's usually a deeper section below the outlet pipe (the sump). Leaves, gravel, and silt drop into that sump instead of going down the pipe, which keeps the line from clogging. Then the water flows out to a safe discharge. That's why a basin needs a quick cleanout now and then. More on keeping them clear.

What "storm drain" usually means

The public system: those curb inlets and grates in the street feed the city or county storm drain network, which carries water to creeks and rivers without treatment. That's why nothing but rainwater should go into them. It's also why you generally can't just tap your yard pipe into one without permission. Rules vary by city, and some have specific requirements for curb outlets.

A private yard system: when a homeowner says "my storm drain is backing up," they usually mean their own network of basins, area drains, and pipes that carries water to the curb or another outlet.

Catch basin vs. area drain vs. French drain

Here's where people get mixed up, so here's the rule:

• Catch basin: collects surface water at a low spot, with a sump that traps debris. Good for patios, driveways, and low points in the lawn.
• Area drain: a smaller grated inlet, often without much of a sump. Same job at a smaller scale, common in planters and side yards.
• French drain: a gravel trench with perforated pipe that collects water from inside the soil, not just off the surface. Full comparison here.

Where does it all go?

Every basin and drain needs a legal, safe place to send the water: the curb, a pop-up emitter, a dry well, or a dispersal area. Picking the outlet is often the hardest part of the design. Here are the options.