How to Fix Water Under My Crawl Space

Water under the crawl space can create a number of problems, including seepage into the crawl space and foundation cracks.

Fix Water Under My Crawl SpaceFix Water Under My Crawl Space
In addition, mold thrives in dark, moist areas and can cause health problems down the line. Fixing the issue can be arduous, but may be worthwhile to individuals who can't afford a professional and sometimes costly contractor. Water mitigation is a difficult but workable problem to manage, with the right tools, time and patience.

Remove the plastic vapor barrier from the crawl space, if one is present, by pulling it up from the floor. Properly dispose of it.

Check the crawl space for mold, rotting wood and insects, all signs of long-standing water problems. Fix any major problems related to these conditions before proceeding.

Dig a trench using a small shovel, 8 to 24 inches from the foundation walls and at least 4 inches deep, to protect the crawl space parameters.

Lay a 3-inch socked flex perforated pipe the full length of the trench to remove any water out of the crawl space. A socked flex perforated pipe is a ribbed, flexible pipe designed with many holes to capture the water and move it toward a designated exit, such as a sump pump.

Locate the lowest part of the trench to install a sump pump; this generally requires digging a pit that can hold the pump. Place the socked flex perforated tubing so it will drain directly into the sump pump. Make sure the sump pump removes the water to the outside of the crawl space and away from the foundation.

Cover the pipe in the trench with 1 1/2 inches of pea gravel. Cover the pea gravel in the trench with dirt.

Install a new vapor barrier by stretching it out and covering the entire floor of the crawl space. Cut openings to accommodate any support beams, if needed.

Dig a small trench, about 4 inches deep, around the outside of the house to help prevent water from standing and seeping into the crawl space again. Add landscaping to encourage water to drain away from the house.

Things You Will Need

  • Small shovel
  • Measuring tape
  • Socked flex perforated pipe, 3-inch diameter
  • Sump pump
  • Pea gravel
  • Vapor barrier, 6-mil vinyl


  • Investigate the reason behind the water under the crawl space. Rain or water-soaked grounds and poor-draining soil are usual causes.
  • Wear safety eye gear when digging under the house.
  • Consider a rebreather when you work in an area with restricted ventilation.


  • Be careful when dealing with black mold in the crawl space. Call a professional to handle the problem if there is an excessive amount.

About the Author

Caroline Adams has been a professional writer and educator since 1980. She has published articles on health-care risk management and continuing education for health-care professionals. Her credentials include a nursing degree, a B.A. in pre-law, a M.A. in health-care law and a M.Ed. from DePaul University. She has taught at several colleges and universities in the Midwest including the University of Illinois and DePaul University.