Water damage, by source
When desert runoff pushes through a door, garage or block wall, it brings soil and street water with it, and the cleanup follows stricter rules than a broken pipe inside the house.
Valley storms drop a lot of rain on ground that sheds it quickly. On Sept. 8, 2014, moisture from Hurricane Norbert produced 3.30 inches at Sky Harbor in about seven hours, the most on any calendar day since Phoenix records began in 1895, and a trained spotter reported 6.09 inches in northwest Chandler. Rain at that rate runs across yards, driveways and streets instead of soaking in, and it enters houses at the lowest openings: garage doors, sliding-door tracks, weep screeds at the base of stucco, and gaps under block walls.
Washes are the other route. Cave Creek's Code of the West warns that a home built in or near a dry wash may take runoff through the house, and Fountain Hills has washes that flood during rain on their way to the Verde River. In Ahwatukee, the Flood Control District and the city mapped flood-hazard spots fed by South Mountain runoff. A house next to a channel that is dry for most of the year can still sit in its path for an hour after a storm.
When remnants of Priscilla and Raymond moved over the Valley in October 2025, Sky Harbor logged 3.26 inches and the Flood Control District gauge in Gilbert caught 3.15 inches in 24 hours.
The S500 water damage standard treats floodwater from outside as Category 3, the same group as sewage, because it has crossed lawns, streets and drainage systems before reaching the floor. In practice that changes the job. Carpet and pad it soaked are normally removed rather than dried, drywall is cut above the wet line in a flood cut, and hard surfaces are cleaned and treated before drying equipment starts. Questions about health belong to a doctor; the restoration side is about which materials can be kept.
Owners can do a few things safely while waiting: stay out of standing water where power may be live, move dry belongings up and away, and photograph the water line on walls and furniture. Skip the hose and the shop vacuum on outside water, and keep children and pets out of the affected rooms. Pulling out soaked rugs, cushions and boxes is reasonable if you wear gloves and boots, but leave carpet pad, drywall and cabinets for the contractor's extraction crew to assess.
Many newer subdivisions move storm runoff through shared basins and culverts. During the Oct. 12, 2025 storm, floodwater broke through block walls and flooded at least four homes in a subdivision near Ellsworth and Broadway roads in Mesa; residents blamed a clogged culvert maintained by an HOA and said they had no flood insurance. A perimeter wall can act as a dam until it fails, then release water all at once against the back of a house, so the first wet room is often the one facing the yard.
Sandbags help at doorways and garage thresholds when they are placed before the storm. Scottsdale offers free sand and bags at two self-service city locations during monsoon season, and Tempe keeps sand and bags available around the clock at 1001 N. Rio Road and at the Benedict Sports Complex. A double row across a garage door, with plastic sheeting under the bags, slows water long enough for it to find a lower path around the house.
Standard homeowners policies commonly exclude surface water from outside, which is why flood coverage is a separate policy. Scottsdale keeps elevation certificates on file for most structures in the FEMA 100-year floodplain and publishes substantial-damage information, both of which matter if a flooded house needs major repair. Owners elsewhere can ask their city or the county Flood Control District what is on record for their parcel. The insurance claims page covers what to document and what to ask the insurer about flood versus other water damage.
Once materials are removed and surfaces cleaned, the house is dried with dehumidifiers and air movers and checked daily with meters. Slab floors and the base of block walls release water slowly, so drying after a flood often runs longer than after a clean-water leak. The drying and dehumidification page describes how contractors decide a room is finished.
Flood maps change as projects are built. A Maricopa County Flood Control District project along Rawhide Wash, from Pinnacle Peak Road to half a mile north of Happy Valley Road, added channel improvements and flood walls to remove more than 850 homes and buildings from the floodplain; construction finished in February 2025 and the map revision was still pending. Owners near a wash where work has been done can ask whether their flood zone has changed, since the zone affects insurance requirements and the rules for rebuilding after serious flood damage.
Usually not when water rises from outside and comes in at ground level; that is generally flood insurance. Rain entering through storm damage to a roof or window is often treated differently. Policies vary, so read the exclusions and ask the insurer before work begins.
Small amounts on a garage slab can be squeegeed out with gloves and boots on. Once outside water has soaked carpet, drywall or cabinets inside the house, removal and cleaning should be left to a restoration contractor, and any questions about health go to a doctor.
Before storms are forecast, not during one. Place them across garage doors and low doorways with plastic sheeting underneath. Scottsdale and Tempe, among others, offer free sand and bags during the season.