Flood Bags
Flood Bags: Fast, Reliable Protection Without Sand
Flood bags are lightweight, water-activated barriers that replace traditional sandbags. StormBag is a FEMA and DHS-approved flood bag made in Chico, California — as seen on Shark Tank.
What are flood bags?
Flood bags — also called sandless sandbags or water-activated sandbags — are compact fabric barriers that ship flat and dry, then absorb water on contact to form a heavy flood barrier. Instead of sand, flood bags use a super-absorbent polymer that locks water into a gel matrix, giving you sandbag-equivalent mass without the sand.
The name "flood bag" is used interchangeably across the industry with "sandless sandbag" and "water-activated sandbag." Homeowners search all three depending on how they first heard about the product. What matters is the underlying technology: polymer-core bags that go from a 1-pound flat pack to a 33-pound flood barrier in three to five minutes.
Why flood bags replaced traditional sandbags for most homeowners
Traditional sandbags require sand, shovels, physical labor, and time you may not have when a flood warning drops. In a fast-moving flash flood or storm surge event, the local hardware store often runs out of sand before homeowners can respond. Flood bags solve that supply chain problem — a case sits flat in a garage or closet for years and deploys with a garden hose in minutes.
The tradeoff: flood bags cost more per bag than raw sand, and they need fresh water to activate. For most residential situations — protecting doors, garages, patios, basements, and window wells — the time and storage savings dominate. For large industrial applications where labor and sand supply are already in place, traditional sandbags still win on raw cost.
How flood bags work
Every flood bag is built around the same core principle: a super-absorbent polymer (SAP) inside a woven fabric shell. The polymer is inert when dry — think of a small pouch of what looks like sugar crystals. On contact with fresh water, the crystals swell to hundreds of times their original volume, locking water into a stable gel. The fabric shell holds the gel in place, and the stitching pattern controls how the bag expands so it lays flat, stacks evenly, and holds shape under pressure.
To deploy a StormBag, you either place it dry in the path of moving water (it activates on contact) or pre-hydrate it in a bucket, wheelbarrow, or bathtub. A submerged bag reaches full mass in three to five minutes. See the step-by-step deployment video for wall-building technique.
What flood bags protect against
Doorways and thresholds
Front doors, back doors, patio sliders — the most common flood entry point in residential flooding.
Garage doors
Single and double garages are wide, low openings that flood first. See our garage kits.
Basement window wells
Below-grade windows are high-risk in heavy rain and snowmelt.
Storm drains and inlets
Divert flow away from vulnerable openings. Used by post-fire road crews on burn scars.
Leaks and spills
Broken pipes, appliance failures, roof leaks — flood bags absorb up to 4 gallons each.
Construction sites
Erosion control and stormwater BMPs — see SWPPP applications.
Flood bags and salt water
StormBag flood bags cannot be hydrated in salt water — the polymer needs fresh water to activate. But once hydrated with fresh water, StormBags work to repel salt water and are effective against storm surge, coastal flooding, and hurricane-driven brackish backflow. If you're on the coast, pre-hydrate in a wheelbarrow with tap water before deployment. Read the full technical breakdown in flood bags for coastal and salt-water flooding.
How many flood bags do I need?
Each StormBag flood bag covers roughly 14 inches of linear width at about 4 inches of stacked height. A standard front door needs 6 bags for 8 inches of protection. A double garage door needs 24–30 bags for 12 inches of protection. For an exact count based on your opening width and expected water height, use the StormBag Sandbag Calculator.
Flood bags vs Quick Dam vs FloodSax vs Sandbaggy
The flood-bag category has real competitors. All use similar polymer technology but differ on approvals, country of origin, and support. StormBag holds both FEMA and DHS approvals, is manufactured in Chico, California, and has been tested by the Salt Lake City Bomb Squad and the National Guard. Full comparison in our 2026 sandless sandbag buyer's guide and the head-to-head StormBag vs Quick Dam breakdown.
Where to buy flood bags
StormBag flood bags ship direct from Chico, California. Available in loose 10-packs and 25-packs, plus pre-configured door and garage kits. Order online at the StormBag store — orders placed before noon Pacific typically ship the same day during storm season.
Get flood bags before you need them
The best time to buy flood bags is before the storm forms — when supply is stable and shipping is fast. A case of StormBags stores flat for 5 years dry.
Shop StormBag Flood Bags