• Floor drains and sumps.
• Joints where basement walls and floor come together.
• Cracks in basement walls and floors.
• Holes in the foundation wall for pipes and wiring.
• Exposed earth or rock surfaces in the basement
• Well water.
• The US EPA and the Surgeon General recommend that all homes be tested for their
• radon levels below the third floor.
• Install a sub-slab ventilation system.
• Cover exposed earth with a polyethylene air barrier.
• Seal all cracks and joints in the foundation wall and floor slab with caulking or foam.
• Install a self priming drain or gas trap in floor drains leading to a sump or to drainage tiles.
• Remove radon from well water using activated charcoal filters or aeration units.