First Steps After a Monsoon Storm Floods Your Phoenix Home

What should I do in the first hour after storm water gets in?

Make people safe, then the building, then document. Stay out of water that has reached an outlet, a cord or an appliance, cut power to the area only if the panel can be reached safely and dry, photograph every room before anything is moved, and keep children and pets off the wet floor.

Floodwater and electricity in the same room is the hazard that turns a cleanup into an emergency room visit. If a cord, a power strip, a washer or an air handler at floor level is standing in water, leave the room and deal with power first.

Then slow the flow if it is still coming in. A towel roll or a sandbag at a door threshold buys time while the cell passes, and anything you lift off the floor in the next ten minutes will not need cleaning later. Boxes, suitcases and stored paper are the first casualties and the easiest to save.

Photograph before you tidy: wide shots of each room, then close shots of the tide line, the silt in the grout and the soaked baseboard. A crew cannot photograph what you have already carried outside. Then call: phones here are answered through the night, and a crew is sent as fast as one is available.

• Do not use a household vacuum, shop vac or carpet machine on runoff
• Do not switch on an appliance or air handler that has been standing in water
• Do wear boots and gloves you are willing to throw away if you move anything yourself

When is monsoon season here, and what can one storm do?

Arizona's monsoon runs June 15 to September 30 on the National Weather Service calendar. Storms inside that window are short and violent: microbursts, straight-line wind, blowing dust, lightning and flash flooding in washes and low streets. The wettest calendar day ever recorded at Sky Harbor is 3.29 inches, on September 8, 2014.

The season's power comes from how little time it takes. Recent normals put annual rainfall at Sky Harbor near 7.22 inches with roughly 2.43 inches of it falling during the monsoon, so a meaningful share of a desert year's rain arrives in a handful of storms rather than in steady winter weather.

September 8, 2014 is the yardstick. Moisture from Hurricane Norbert moved over the state, sections of Interstate 10 and Interstate 17 closed, water stood deep enough on I-10 west of downtown to stop traffic, parts of Chandler recorded close to six inches, and flash flooding killed people elsewhere in Arizona that day. Records at Sky Harbor go back to 1895, and nothing has topped it.

Storms also arrive in clusters, and power cuts travel with them, so drying equipment sometimes waits on the utility rather than on the crew.

Why is street and wash runoff the dirtiest category of water?

Because of where it has been, not how it looks. Runoff crosses roads, yards, alleys and washes and mixes with oil and fuel residue, fertilizer, pesticide, animal waste and storm drain contents. The ANSI/IICRC S500 standard puts rising surface water in Category 3, grossly contaminated, whatever its colour.

Clear water misleads people every season. Category describes the source and the condition, and tap-clean water becomes contaminated the moment it runs across a street. A closed garage at 105 degrees then does the rest, because warmth is exactly what the contents of that water want.

This is why a crew turns up in protective equipment, sets containment and disinfects rather than pointing fans at a flooded garage. It is also why the do-it-yourself version goes wrong: a household vacuum spreads what it picks up, a carpet machine pushes contaminated water deeper into pad, and shoes carry silt into dry rooms.

• Taken out: carpet pad, cardboard, particleboard, wet insulation, drywall in the soaked band
• Cleaned, disinfected and dried: slab, block, tile, metal, sound framing, sealed hard surfaces
• Decided case by case: solid wood furniture, and anything with a motor or a circuit board

Where does storm water usually get into a house here?

At the lowest opening it can find. Garage doors with a worn bottom seal, side doors with a flattened sweep, patio sliders, sunken entries and low thresholds take most of the runoff, while wind-driven rain comes in higher up, around window heads, under lifted tile and through a roof opening the storm itself made.

Two different problems arrive in the same hour, and separating them helps. Runoff comes in at floor level and leaves silt; wind-driven rain comes in overhead and leaves stains on ceilings and down the inside of walls with no plumbing near them. The repairs, and often the insurance conversation, go different ways.

Local geography decides who gets the floor-level version. Hillside washes off the Phoenix Mountains drain through Sunnyslope, runoff from the north face of South Mountain crosses low ground toward the Salt River bottom, washes come down through Ahwatukee, and engineered channels take the rest: the Arizona Canal Diversion Channel of the mid-1990s, and Scottsdale's Indian Bend Wash Greenbelt, built in stages from the 1970s as a grass-lined floodway.

No crew can tell you what flood zone your address is in, and none should try. Check the property's FEMA flood map and ask your city's floodplain office; in Maricopa County the Flood Control District handles floodplain permitting for some communities while Phoenix, Glendale, Peoria, Scottsdale, Tempe and Paradise Valley run their own programs.

Never drive into a flooded wash, whatever the detour costs

Turn around, don't drown. Water running across a road hides how deep it is and how fast it moves, it has already undercut the pavement in places, and a vehicle floats sooner than drivers expect. Never go around a barricade: the barricade is there because somebody has already measured what is behind it.

A wash that was dry sand an hour ago can be chest-deep and moving when a storm cell twenty miles upstream drains into it. You will not see that from the road, because the rain may never have fallen where you are standing. It is the most dangerous part of a monsoon storm and the easiest to avoid.

The same goes on foot. Running water a few inches deep takes your footing, submerged grates are open hazards, and the water is Category 3 with a current in it. Keep children and dogs well back from a running wash for as long as it moves, and remember that no amount of water in a garage is worth the drive home through a flooded dip.

Does my homeowners policy cover a monsoon flood?

Usually not, if the water came across the ground. Standard homeowners policies exclude flood, meaning surface water, runoff and overflowing washes or canals, and cover it only through a separate flood policy. Rain that entered through an opening the wind created is often treated differently, and your insurer decides under your own policy.

The distinction that matters is the path the water took, not the storm that caused it. One thunderstorm can lift tile, drive rain into a ceiling and send runoff under a garage door in the same twenty minutes, and those paths can be looked at under two different policies.

Flood cover comes from the National Flood Insurance Program or a private insurer, and it generally takes about 30 days to take effect, which makes spring the right month to ask your agent. A policy bought while a storm is on radar will not help with that storm. Ask too about a water or sewer backup endorsement, since drains overload in the same hour that streets do.

Whatever you carry, document the loss as though somebody will review it line by line; the Arizona Department of Insurance and Financial Institutions takes consumer questions about homeowners claims.

What happens on the crew's first visit after a storm?

Protection first, then assessment. An opening is tarped or boarded so the next cell cannot refill the building, the wet area is mapped with meters and a thermal camera, water and silt are removed, porous materials that soaked are bagged, and drying equipment goes in before anyone leaves, with readings and photographs recorded.

Tarping and board-up are protection, not repair. They keep tonight's storm out of a building that is already open, and the permanent roof, window or patio-cover work goes to a licensed contractor in that trade. The monsoon storm damage service explains where that line sits.

Assessment goes well past the room you called about: water runs along framing and the top of a slab, so readings are taken in closets, the garage wall shared with the house and the attic above a stained ceiling.

Then the clock matters. EPA guidance points to drying water-damaged areas within 24 to 48 hours to limit mold, and the EPA is also clear that growth may already have started inside that window, so it is a reason to move quickly rather than a promise about the outcome.

What is worth doing before the next June 15?

Most monsoon damage is a maintenance item that waited too long. Clear roof debris and check drains and scuppers before the season, replace worn garage door and door bottom seals, clean out yard drains, confirm the main shut-off valve actually turns, and settle any flood insurance question in spring rather than in July.

Roof work is a roofer's job and worth booking early, because the first storm is when everybody calls. Debris left on a flat or foam roof after one season is the thing that blocks drainage in the next, and ponding water finds a worn coating fast.

At ground level, look at how water would move across your lot. Grading that slopes toward the house, a blocked yard drain, a low threshold or a flattened garage door seal are all cheap to fix in May and expensive to discover in August with silt on the slab.

• Roofer's pre-season check: debris, drains, scuppers, flashing, coating condition
• Garage door bottom seal and exterior door sweeps, replaced rather than patched
• Yard and area drains cleared, and grading sloping away from the house
• Main water shut-off located and tested, with a working flashlight beside it