Water-inflated tubing is a fairly new and very effective emergency method of closing a gap, temporarily raising the height of an existing levee or putting a barrier around a building or between a building and a rising river. Water-inflatable barriers are easier to erect than sandbag levees or walls, take much less time and require little storage space when deflated.

Water-inflated dams have been used widely in industrial applications for containment of oil spills, diversion of water for bridge construction and other large-scale operations. They are available commonly in heights from 2 feet to 6 feet. Some are oval, with one or two internal baffles to prevent rolling; others get their stability from their triangular shape.

Considerations

Commercial inflatable barriers can be found easily on the Internet. Once you know the length of barrier you need, and the depth of water you're trying to keep at bay, the maufacturer or outlet can give you a cost. For comparison purposes, a nundred-foot length of commercially produced barrier would run about $7,000/ for a four-foot high barrier, but closer to $4,000 for one only two-feet high.

At these lower levels, you can make a water-inflated barrier using irrigation tubing, which can be purchased from farm irrigation supply stores. It comes in 1,320-ft. rolls (1/4 mile) in various thicknesses and diameters. Based on quotes obtained in 2012, 22-inch diameter tubing cost about 40 cents per foot. Keep in mind, though, that irrigation tubing is more fragile than a bonafide water-inflated dam and it cannot withstand as much pressure or debris impact. Because the tubing doesn't come with the fittings you'd get with a dam, it can be more difficult to fill and manage. The commercial product is more likely to be reusable.

A water-inflated barrier will generally protect against water that is about 3/4 the height of the barrier. The level of protection is only as high as the lowest point along the barrier. This method is effective only on level sections of ground.

The principle of blocking floodwater with a barrier filled with water can be applied to other containers of different materials and different shapes. Find something that won't roll, scoot along the ground or tip over. Beyond that, you need to consider how and where you'll store your temporary barrier when it's not in use.

Tips to Remember

• Keep the necessary materials on hand. This includes tubing, stakes or other support devices, ties or connectors.
• Be sure you can install the system in the amount of time you normally have to prepare for a flood.
• Have a pump inside the protected area. Even good systems leak. Some water will seep in underground, and rain will fall inside your barrier. You have to pump it out.
• Before each flood season, have a practice run. Find the materials and test the pump. A flood protection system is like a chain; it's only as good as its weakest link. If the barrier across an opening fails, your floodwall or levee is of little use.
• As with permanent levees and floodwalls, you need protection from sewer backup.
• Failure of the system for any reason can result in a forceful rush of flood water into the property. Plan for your safety. Decide in advance when you will abandon a flood fight and save your life.

Using a single irrigation tube

To block an opening or surround a building, lay out a single length of tubing where you want to erect the flood barrier, and fill it with water.

If the water flow from your municipal water system is too low, or you're filling a large section of tubing, you can speed up the process by pumping pond water, pool water or even floodwater into the tubing by using a pump.

Keep the water in by turning up the ends of the tubing. The ends don't need to be sealed, but they must be secured in the up-turned position.

Use heavy objects that don't float to keep the tube from rolling, sliding or shifting. These might include sandbags, concrete blocks or another section of tubing. On unpaved areas, you can drive stakes in the ground to keep the tubing in place. The tube can rest against a strong board placed across an opening.

Stacking tubes for greater protection

Irrigation tubing will not hold back water to the full depth of its diameter. A 22-inch diameter tube may give you only 16 inches of protection. You can get a little higher protection by filling a second tube behind the first one, then laying a third tube in the groove formed by the first two tubes. Brace the lower tubes so they don’t separate, and be sure you’ve closed the ends of the lower tubes securely. Put the tubes in place before you fill them.

Don’t stack these irrigation tubes higher than two deep. The added weight will increase the pressure in the lower tubes and may cause them to rupture. For protection over 2 feet, use comercially available water-inflated dams or other systems.