by Nick Gromicko, CMI® and Will Decker

A standpipe is an open-ended, metal pipe that can be screwed into a basement floor drain to permit the flow of water back up as high as necessary, thereby delaying or preventing a basement flood. These simpler, less expensive alternatives to check valves, standpipes are a throwback to the mid-20th Century, when the county drain system couldn’t handle all the storm water. They are typically 2½ to 4 inches wide and rise several feet above the floor. Note that "standpipe" often refers to a wide variety of mechanisms but this article refers to standpipes found in basements.

Water intrusion can come from a surprising number of sources:  tree roots that penetrate subterranean piping; accumulated grease and waste; rising riverbanks; and inadequate municipal sewer systems. Standpipes and other waterproofing methods should be considered by every homeowner, especially those who reside in wet climates, as moisture can ruin thousands of dollars' worth of drywall, furniture, carpets and electronics, and contribute to the growth of mold.

As a result of their simple design, standpipe inspection is fairly straightforward. Note the following defects that are sometimes observed:

  • broken seal or cross-threaded point of attachment where the standpipe attaches to the floor;
  • trip hazard. As with any protruding pipes, standpipes can be easily tripped over or walked into, which is why it’s important to remove them when they aren’t needed. In most cases, homeowners have enough warning time to attach the standpipe before it’s required; and
  • lack of watertightness. If the standpipe has any damaged seals, or if it wasn’t constructed properly (as may be the case with homemade models), it may leak, which makes the assembly unsurprisingly ineffective.

Some plumbers and contractors warn that if the standpipe is more than 18 inches from the floor, it can create pressure that will cause the sewer lines to crack, basement walls to fracture, and the entire house to collapse into the foundation. While these fears are widespread, they are largely unfounded.

Homeowners who wish to prevent basement water intrusion can also try the following precautions. 

  • Ensure that the roof's gutters and downspouts are in good condition, free from leaves and debris, and that they drain downslope at least 6 feet away from the house. Landscapers should be warned not to remove or damage downspouts, which should be secured with sheet metal screws.
  • Purchase a quality dehumidifier, with at least 65 pints-per-day's capacity, for the basement. An optional drain hose will allow the water to drain directly into a floor drain or sink, saving you the trouble of having to empty the dehumidifier when it fills.
  • Purchase a sump pump, preferably one equipped with a 120-volt UPS battery-backup power supply, rather than an inexpensive, 12-volt battery. In addition, it’s wise to install a backup sump pump to place beside and 6 to 8 inches higher than the main pump in order to provide extra drainage flow, or in case the main sump pump fails.
  • Consult with an InterNACHI inspector.

In summary, standpipes are simple, inexpensive and effective mechanisms used to prevent that backflow of water from basement floor drains.