Burst Pipes, Flooded Homes, & What To Do

How Does Nine Inches of Water in Your Home Grab You?

Ever wonder just how fast a burst water pipe can flood your home? I saw it firsthand recently at a neighbor’s house and it got me to thinking about the actual numbers—because the damage was impressively devastating—the whole interior needed to be gutted and rebuilt. The numbers get real big real fast! Here is what I came up with.

When you turn on your hose (on public water—private well systems can vary) I usually get a flow rate of 5 gallons per minute (gpm). That’s the maximum a typical home system will provide, coming out of a typical ½” supply pipe, because there are no flow restrictors on the hose bibb. Let’s say your washing machine hose (the basic black rubber kind) in your upstairs laundry bursts shortly after you leave for work (because it’s been under full time pressure for 8 years now, and it’s only a rubber hose, not a copper or plastic pipe). Instead of an unrestricted flow of 5 gpm I will use 3 gpm because it’s “squirting” out of the slit with some restriction to free flowing. Remember, this is water under 40-80 psi of pressure. Eight hours later you come home to see water coming out from under your front door. How much water just soaked your home?

1.      One U.S. gallon = 0.13368 cubic feet

2.      3 gpm x 60 minutes x 8 hours = 1440 gallons = 192 cubic feet of water

3.      192 cu.ft. covers 2304 sq. ft. (192 x 12) with ONE INCH of water! (in other words, enough to soak all your carpeting, all your hardwood floors, damage all your drywall ceilings and a lot of your walls, cabinets, furniture, etc.)

That’s one inch of water over every square foot of two levels of the typical sized house. Now, I don’t know how the water did it, but at my neighbors house, a joint gave way in the master bath and instead of all the water finding a path down the stairways it managed to soak every square foot of flooring (and thus the ceilings below) on ALL three levels! It quickly finds little cracks in the subfloor and soaks the ceilings below, while continuing to spread along the current floor, finding more cracks (and yes, stairways) to gravity feed to its ultimate destination out the front door and basement. Until the ceilings give out and soak the floors below, the water migrates to the side walls and gives that drywall and insulation a good soaking. In my neighbor’s case the joint froze because the house was empty, the water on, and the heat off or failed, for whatever reason. Also, no one noticed the flood taking place for 36 hours! Let’s run those numbers:

1.      It’s a 28’ x 42’ house with three levels (finished basement included) = 3500 sq. ft.

2.      3 gpm x 60 minutes x 36 hours = 6480 gallons = 866 cu. ft. of water

a.      Take 12 slices of those 866 cu.ft. to get 10392 slices of water 1” deep.

3.      Spread over 3500 sq.ft. = THREE INCHES (10392/3500) of water over every sq.ft. of house, or NINE INCHES if it all found its way into the basement!

4.      To add insult to injury the water/sewer bill just jumped up $55 for the month!

Precautions to take:

1.       It’s impractical to turn off your water every time you leave your house, but when you leave town for the weekend or longer, especially in winter, consider turning off your main shutoff. If your heat fails while away, at least you won’t also have a flooded home.

2.       If you don’t want to turn off the main shutoff, consider at least turning off the following fixtures that have a higher rate of failure:

a.       Toilet tank supply valves. Toilet hardware is notorious for failure—you know the “running” toilet noise—well years ago, I saw the effect of what one toilet overflowing could do in half a day’s time at another neighbor’s house.

b.      As I recommend at every inspection, IF you leave your washing machine supply valves on full time, then replace the black rubber hoses (not rated for unlimited full time pressure) with the braided stainless steel type.

c. Individual sink shutoffs, or at least the ones your pet or house sitter won’t need.

3. If you need water on for your pet sitters you can still turn off the cold water supply at the water heater—at least that way you have a 50/50 chance that a failure will be on a closed hot water supply line/fixture and not flood your home.

4. Lastly, for any extended time away, absolutely have a trusted neighbor check in on your house once, preferably twice a day. Not just keep a “watchful eye” from across the street but someone who will come in, walk around, listen for suspicious noises, and go in the basement to check for impending trouble. Every hour a burst pipe/valve/fixture goes unnoticed is 120 to 300 gallons of water!