Even if your home was somehow completely protected from all groundwater flooding, your basement will still eventually flood. The reason is this: your home is filled with pressurized water. It resides in your plumbing pipes, sinks, toilets, tubs, showers, washing machine hoses, water heaters, and in many other locations throughout the home. And because water will always run downhill, major flooding in any part of the house is going to end up in the basement.
Bursting Washing Machine Pipes
Bursting washing machine hoses are inevitable- especially if you're not turning off both valves for your washing machine every time you do your laundry. Your washing machine hoses are pressurized at 50-80 pounds per square inch, and when they fail, you can expect 650 gallons per hour to shoot out of just one of these 3/8" hoses. And since water weighs about 8.33 pounds per gallon, you can expect more than two and a half tons of water!
If you're not at home when this happens, the problem can be extremely serious. In once case, a basement contractor reported a home where the washing machine hose burst while they were away on vacation. They came back to see that water had risen right up to the windows! In another situation, a hose burst on the second floor: as the water ran down through the ceilings, it resulted in $40,000 in damage.
Consumer-grade washing machine hoses are typically cheap and of poor quality. Under the best conditions, you an expect them to last about 4-5 years. Instead of taking this kind of risk, install industrial-strength washing machine hoses with brass end connections. They're well worth the money, and they often come with warranties measured in decades instead of years.
Failing Water Heaters and Cold Water Storage Tanks
You can expect your water heater to last for about seven years- most homes replace their water heaters many times over the life of the structure. Unfortunately, when water heaters fail and leak, they don't simply empty out. Instead, they attempt to automatically refill themselves, resulting in an unlimited amount of water leaking into the basement. It's common for a basement contractor to see several inches of water that have collected on the floor from a leaking water heater.
Cold water storage tanks can also create a problem in the basement if they leak. And in the summer, condensation can continuously form on their surface, draining to the basement floor. Install a plastic ring around your water heaters and cold water storage tanks that drain into your existing perimeter waterproofing system. Any water that emerges from the flood will enter this system and be automatically sent out of your house.
If this is not possible, you should still install a ring around the heater. Follow up by placing an alarm within the ring that will sound off when it comes into contact with flooding water, giving you fair warning if there's a problem.
Other Plumbing Leaks
Your house is full of plumbing, and you can never be sure that you're protected from it all. However, if your sump pump has an airtight lid with a drain installed on top, you can rest easy that the flood will be kept under control. Upon request, some contractors will even leave a special water-detecting alarm on the floor. This alarm will sound off when water contacts it and can even be set to work with your existing alarm system to have you reached by phone if you're away.