Before monsoon season, have the sewer line scoped and cleaned, confirm low floor drains are protected by a backwater valve, clear the roof drains and check that the overflow drains or scuppers are open, and know your water shutoff. Ask your agent about flood coverage early, since it has a 30-day wait.
1. Get the sewer line scoped and cleaned
A camera inspection shows roots, grease buildup and sags before a storm turns them into a problem. Our overview of preventing sewer backup before monsoon explains the reasoning, and what a sewer cleanout is shows where a plumber gets access. Find the cleanout on your property now, and make sure it isn't buried under landscaping or a parking stall.
2. Protect low floor drains with a backwater valve
The fixtures that flood first in a surcharged sewer are the lowest ones: floor drains, mop sinks, restrooms and kitchen drains below the level of the next upstream manhole. Code addresses this with backwater valves, and when code requires a backwater valve turns on that elevation rule. If you have never had the question answered for your building, ask a plumber to check the fixture elevations against the manhole.
3. Clear the roof drains and check the overflows
Roof drains are the first line of defense on a flat roof. The 2024 International Plumbing Code, in section 1108.1, says that where roof drains are required, secondary (emergency overflow) roof drains or scuppers "shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason."
The same section says the secondary system's discharge has to be separate from the primary system and located "above grade, in a location that would normally be observed by the building occupants or maintenance personnel." In practice, if you see water coming out of an overflow outlet, treat it as a sign the primary drain is blocked. Before the season, have someone clear debris from the drains, strainers and scuppers, and confirm nothing was covered during a roof repair. Your city's adopted plumbing code and your building's design govern the details.
4. Secure the site
The Weather Service recommends securing loose outdoor furniture and garbage cans, or moving them indoors, before the season. It also says thunderstorm wind gusts in the Southwest almost always exceed 40 mph. Walk the lot before the season and clear gutters, catch basins and any grates you're responsible for.
5. Know your water shutoff, and get the paperwork done early
Your staff should know where the main water shutoff is and who is authorized to close it. Our page on planning a commercial water shutoff covers how a shutoff affects a building.
On coverage, the Flood Control District notes that National Flood Insurance Program policies are available to commercial owners and renters. FEMA says there's typically a 30-day waiting period before a policy takes effect, unless the coverage is required by a government-backed lender or tied to a community flood map change. Ask your insurance agent about it well ahead of the season, and ask what your current business policy does and doesn't cover.
After a storm
If water gets in, the district's recovery steps apply to a business as they do to a house: call your insurer, photograph the damage before repairs, and turn off the water and electrical sources, but never try to switch off electricity while standing in water. Get professional help. If sewage is involved, see what to do first after a flood or major water leak.
HQ handles commercial plumbing with 24/7 emergency service. We're licensed and insured, and we give free estimates and upfront pricing before work starts.