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Choose sandbags for flooding, and know their limits

By the Plain Prepper editors. Updated 2026-10-18.

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Quick answer

For a flood wall you fill yourself, Sandbaggy's 14 x 26 inch woven polypropylene bags take a recommended 50 lb of sand and resist about 2,000 hours of sunlight. Burlap bags biodegrade but break down in sunlight in about a month. Quick Dam's water-activated bags and barriers need no sand: they swell with water in about 10 minutes, but Quick Dam says they are not for salt water. Sandbags slow water; they do not make a home safe in a flood, and Ready.gov says to evacuate when told to.

What sandbags can and cannot do

Sandbags and flood barriers are meant to contain and divert water away from doors, garages and low spots. They are no reason to stay in a home that officials tell you to leave. Ready.gov says to evacuate if told to do so, move to higher ground or a higher floor, and never walk, swim or drive through flood waters. It notes that just six inches of moving water can knock you down and one foot of moving water can sweep your vehicle away.

Plan bags for the places water enters first, and have them on hand before the season starts, since a bag you cannot get to in time does not help.

Woven polypropylene bags

Polypropylene is the common fill-it-yourself bag. Sandbaggy lists its 14 x 26 inch woven polypropylene bag at 10 mil thick, with double-stitched seams, an attached tie string and UV protection rated for about 2,000 hours of sunlight. Sandbaggy says the bag can hold up to 100 lb but recommends a 50 lb sand fill, about 0.5 cubic feet, which fills out to roughly 12 x 18 x 3.5 inches.

Sandbaggy describes the bag as 98 percent waterproof and reusable. A 50 lb bag is a real load to move, so plan for help.

Burlap bags

Burlap is the natural choice. Sandbaggy lists its 14 x 26 inch burlap bags as 9 ounce jute that is 100 percent biodegradable, holds 50 lb or more, and comes with a tie string. The trade-off is lifespan: Sandbaggy says burlap begins to biodegrade after approximately one month in direct sunlight.

Pick burlap for short jobs where the bags will be removed or left to break down, and polypropylene for bags that sit out through a season.

Water-activated bags and barriers

Water-activated bags skip the sand. Quick Dam says its Flood Bags contain a super absorbent powder that swells and gels when wet, growing to 12 x 24 x 3.5 inches in about 10 minutes after absorbing 4 gallons of water, and can be stacked in a brick pattern. Its Flood Barriers come in 5, 10 and 17 foot lengths, absorb 4, 8 or 13.5 gallons depending on length, grow to 3.5 inches high, have a built-in wedge to help prevent rolling, and can be stacked in a pyramid for a higher wall.

Quick Dam warns they are not for use with salt water, because a chemical reaction causes deflation. Where flood water may be salty, such as along the coast, choose sand-filled bags. Quick Dam describes the bags as non-toxic and says they decompose over time.

How many to buy

Measure the opening you want to protect. A Quick Dam 5 foot barrier covers a 5 foot doorway at 3.5 inches high in one piece. Sandbaggy's filled polypropylene bag is about 18 inches long, so a 5 foot run takes about four bags per row, and each extra row raises the wall. Arithmetic like this is a starting point; follow local emergency managers on how high and how wide to build.

What to look for when you buy

Questions people ask

How much sand goes in a sandbag?

Sandbaggy recommends 50 lb of sand, about 0.5 cubic feet, in its 14 x 26 in. polypropylene bag, which it rates to hold up to 100 lb.

Do water-activated sandbags work?

Quick Dam says its bags swell to 12 x 24 x 3.5 in. in about 10 minutes after absorbing 4 gallons, but warns they are not for salt water.

Burlap or polypropylene sandbags?

Polypropylene lasts longer outdoors; Sandbaggy rates its poly bags for about 2,000 hours of sunlight, while its burlap begins to biodegrade after about a month in direct sun.

Should I stay home if I have sandbags?

No. Ready.gov says to evacuate if told to, move to higher ground, and never walk, swim or drive through flood waters.

Sources

• Floods, Ready.gov (maker page: www.ready.gov/floods)
• 14 x 26 Woven Polypropylene Sandbags for Flooding (sandbaggy.com), Sandbaggy
• 14 x 26 Burlap Sandbags (sandbaggy.com), Sandbaggy
• Flood Bags (quickdams.com), Quick Dam
• Flood Barriers (quickdams.com), Quick Dam

Sources checked 2026-10-18.