Pressure Washing Runoff in Miami-Dade: What Can Go Down the Storm Drain?

A driveway, a dumpster pad, a restaurant sidewalk: the dirt comes off, and the water heads for the nearest grate. That grate belongs to the storm sewer, which is built for rain, not to the sanitary sewer that carries wastewater to treatment. Miami-Dade notes that runoff from the urban landscape can carry pollutants into lakes, canals and Biscayne Bay (Miami-Dade County). That is why wash water is a regulatory question, not just a mess to sweep up.

What the rules say

• Miami-Dade County. The county code makes it unlawful to discharge “domestic sewage, industrial waste, liquid waste, or other waste” into a sewer designed to carry storm water (section 24-42.4 of the Code of Miami-Dade County, shown in the county’s 2025 ordinance file). The county’s environmental division (DERM) takes reports of liquid discharges into storm drains 24 hours a day (DERM).
• Federal stormwater rules. EPA’s stormwater regulations define an illicit discharge as any discharge to a municipal storm sewer that is not made up entirely of storm water, with limited exceptions (40 CFR 122.26(b)(2)).
• State guidance. The Florida Department of Environmental Protection (FDEP) states that discharging wastewater to stormwater systems, such as drains, ditches and retention areas, or to surface water is prohibited without an NPDES wastewater permit (FDEP).

The FDEP guide is written for mobile vehicle and equipment washing. If you wash fleets or equipment, it applies directly. For houses, roofs and flatwork, its methods are a good reference, and DERM can answer questions about a specific setup.

Before you start a job

1. Plan the water first. Decide how you will collect it and where it will go, and get any approvals, before you turn on the machine.
2. Walk the site. Find every storm drain, swale and ditch, and look at the slope to see where the water will run.
3. Use less. High-pressure, low-volume equipment means less water to manage. Sweep up loose debris first.
4. Go easy on chemicals. FDEP suggests the minimum amount of detergent, close to pH neutral and rapidly biodegradable, and avoiding strongly acidic or alkaline products or ones with petroleum distillates or chlorinated solvents.

Containing and disposing of wash water

FDEP lists common containment tools: booms or berms around a drain, drain covers and mats that seal the grate, portable containment pools, and wet/dry vacuums or pumps to pick the water up. Inflatable pipe plugs belong only on private property, not in public storm drains. For disposal, the guide lists four options:

• A closed-loop recycling system, with its sludge and reservoir water disposed of properly.
• The sanitary sewer, with prior approval from the wastewater utility and the property owner.
• Land or ground, only for small, infrequent amounts that do not run off. Repeated use of the same area may require a permit.
• Surface water, which requires an NPDES permit and is generally not practical.

Collect solids, such as paint chips and grit, and dispose of them properly. If a spill could reach a storm drain, contain it and report significant spills to the local FDEP office or the county. Fertilizer has its own drain rules; our article on fertilizer rules in Miami-Dade covers them.

Why it matters for your business

Property managers and HOAs often ask how you handle runoff, and runoff that damages a customer’s plants or a neighbor’s property is a liability question. When we quote, tell us what you wash, which chemicals you use and how you recover water. See our pressure washing insurance page for the coverage side.