Ask the Carpenter: What to do when you find radon in your water

Ask the Expert Home Improvement
. AP

Q. We built our home 32 years ago, and our well tested high for radon recently. We must mitigate. What is the best course of action? How do we find a reputable company? We probably should have the air quality tested also.

K.G., Hopkinton

A. Radon can be removed from water by aeration or carbon filtering at the point of entry of your waterline. Aeration removes radon by blowing air up through the water. As the air bubbles rise through the water, they strip it of radon and carry it out the top of the tank and through a vent pipe to above the roofline. While this unit will cost more upfront, it has no associated disposal costs. An aeration system will remove about 99 percent of the radon and will cost $4,500.

Activated carbon removes radon as well, but it remains on the surface of the filter, where it continues to decay and give off radiation. Eventually, this filter becomes a low-level radioactive source requiring special disposal. A double charcoal system can remove up to 90 percent of the radon and costs about $1,650.

For liability reasons, I can’t recommend a radon mitigation company. What I do recommend is that you check out any company with the Better Business Bureau before you hire them.


Q. We had a sump pump system installed about four years ago. The contractor told us our land dips inward, toward the house. We’re the third house up at the bottom of a hill. Because of that, they had to direct the water flow out to the sidewalk. In the good weather, it’s fine, but in the winter, it freezes. The swath was about 3 feet wide. My husband applies ice melt and sand and puts a sawhorse where it freezes, so people will know not to walk on it. Someone must have complained to the city inspector, because we received a warning from him: Correct it or be fined. The inspector came to the house and told us we could have the water flow go into the driveway, and then onto the sidewalk. We did that, but now the swath is even wider — at least 6 feet. A “friend of a friend’’ told my husband he could dig a 6-foot trench in our driveway and have the water go underground. My gut instinct is telling me that’s illegal.

We’re an older, partially disabled couple, and it’s getting more difficult for my husband to keep up with the freezing water. We want to get this issue resolved before the winter. What can we do to fix this?

L.Y., Everett

A. OK, I would connect my sump pump discharge pipe to a dry well. A dry well will give your sump pump water a place to go when you have hardscape issues (patios, driveways, walkways), which you do. If installed correctly, it also will work in freezing temperatures. Installing a dry well is not hard, but it is labor intensive if you do not have access to a backhoe.

This is actually a pretty straightforward fix, assuming you have the room to do it.

Install the dry well as far away from your foundation wall as possible. You will need to dig a trench from the discharge pipe to the dry well location.

If you are going to hire someone with a backhoe or excavator machine, consider having the trench installed deeper than the frostline as well. I did this for a client; we installed the discharge pipe 24 inches below ground, so its hidden and less likely to freeze.

For my dry wells, I purchase a 36-inch-round by 48-inch-deep heavy plastic culvert pipe with a heavy-duty plastic lid for future cleaning and inspection.

I drill 3/8-inch holes all around the sides of the pipe. The bottom is open and will sit on gravel.

I dig the drywell pit 12 to 24 inches larger all around, line the pit with landscape fabric to keep dirt from clogging it, fill in the bottom roughly 12 inches deep with 3/4-inch stone, install the plastic dry well, and surrounded it with 3/4-inch stone. Before filling in the final grade, I cover the lid and stone with landscape fabric to keep everything clean.

I purposely kept the dry well empty, not filling the container with gravel, to allow for a higher volume of water.

Rob Robillard is a general contractor, carpenter, editor of, and principal of a carpentry and renovation business. Send your questions to [email protected] or tweet them to @robertrobillard. Subscribe to our free real estate newsletter at