On Sept. 9, 2026, engineers presented the San Tan Valley Area Drainage Master Plan to the Pinal County Flood Control District board. The study covers 68 square miles, including the roughly 35 square miles inside the Town of San Tan Valley. SanTanValley.com reported on Oct. 3 that it names 12 areas where new culverts, channels and retention basins could move stormwater away from roads and homes. None of that work has a price tag or a construction date yet. The board was expected to consider adopting the plan in October.
The engineers found that drainage here was built piece by piece as neighborhoods went in. They counted 267 culverts and 74.5 miles of channels, and many of them do not connect. Their model found 222 homes and other buildings that would have water against them in a 100-year storm, a storm with about a 1% chance of happening in any year.
What the plan does and does not mean for your house
The plan is about roads, washes and neighborhood channels. It does not tell you whether your home is one of the 222. The county’s new map of where water goes in a 100-year storm also does not require anyone to buy flood insurance. If you want to see what is proposed near you, the county’s Sept. 9 presentation has a close-up map of each project area.
What you control is smaller and closer to home: where water lands after it leaves your roof. In a heavy rain, a roof gathers a lot of water and drops it in a few places. If those places drain toward the house, your roof is adding to the problem the county is trying to solve on a larger scale.
A roof-runoff check for a San Tan Valley home
- Watch it rain once. During or right after a storm, walk around the house and note where water pours off the roof. On a tile roof, valleys and eave corners often concentrate it.
- If you have gutters, make sure each downspout is attached and empties onto a splash block or extension that carries water away from the foundation.
- If you have no gutters, look at the ground along the drip line. Washed-out gravel or soil pulled away from the slab shows where water is landing hard.
- Check flat roofs and patio covers. Scuppers and drains should be clear. Water that stands for days on a low-slope roof is worth an inspection.
- Look along block walls and side yards. Spots where roof water and yard water meet and pond are a grading question as much as a roof question.
Flood coverage is a separate subject from your roof. Homes inside town limits became eligible for the National Flood Insurance Program effective July 31, 2026, SanTanValley.com reported. According to FEMA, most homeowners insurance does not cover flood damage. A licensed insurance agent can explain the options for your address.
Want a second set of eyes on how your roof sheds water? Request a free roof inspection or call (480) 808-ROOF (7663). We can check valleys, flashings, scuppers and drip edges and show you where the water goes. More on our San Tan Valley roofing page.
Sources: SanTanValley.com, County Names 12 Flood Trouble Spots Across the San Tan Valley Area (Oct. 3, 2026); Pinal County Flood Control District, Sept. 9, 2026 agenda packet and ADMP presentation; SanTanValley.com, Federal Flood Insurance Now Open to Town of San Tan Valley Properties (Oct. 11, 2026).