1. The inlet is full. That's it.
Roughly 60% of the "we need drainage work" calls we run turn into a vactor visit and nothing else. The sump is packed with mulch, silt, cigarette butts, straws, plastic bags — and the outlet pipe is above the debris line, so water pools until it finally seeps down. A crew pulls up, opens the grate, drops the hose, and 20 minutes later that basin swallows a garden hose test with no backup. Bill's a few hundred dollars per basin.
The tell: after the rain stops, the standing water drains within an hour or two. If it drains at all — even slowly — the pipe network is intact and you've got a cleaning problem, not a construction problem.
2. A pipe run between two structures is choked
Second most common. The upstream basin looks clean, but water still backs up because the pipe going to the next structure is 40% blocked with hardened sediment, roots from a nearby ficus, or in one memorable Doral case, a landscape irrigation head someone jammed in during a repair. This is where hydro jetting earns its keep — 3,500 PSI down the pipe, vactor pulls the debris out of the receiving structure, done in a morning.
The tell: one basin fills fast while the next one 60 feet away barely gets wet. Or CCTV shows the blockage exactly.
3. The system was undersized 20 years ago and the rain got worse
This is the expensive one. Older Broward and Miami-Dade retail centers were designed for a 5-year storm event that doesn't reflect what rolls through now. If your lot floods every time it rains hard — not just once a season — and the basins and pipes are clean, you're looking at retrofit territory: added inlets, upsized laterals, or a new outfall connection. That's an engineer's call, not a vactor truck's.
The tell: chronic flooding in the exact same low spot every storm, and cleaning made no difference the last two times.
Before you call anyone, do this
Walk the lot the next time it rains hard. Photograph where water pools first, where it stays longest, and which grates are actively taking water versus sitting under a puddle doing nothing. That five-minute walk saves an hour of on-site discovery and often tells us before we even get there whether it's a cleaning job, a jetting job, or a call to a civil engineer.
Full pricing on the cleaning side lives on the catch basin cost guide and hydro jetting cost guide. Or see our parking lot drain cleaning service page.
