Featuring America's Home Inspector: Nationally Syndicated Columnist, Barry Stone

What To Do About Drain Flies

Dear Barry: We have a major problem with drain flies under our house. We’ve called a plumber and an exterminator, but both say they’ve never seen this kind of problem before. We’ve also had the septic system pumped and inspected, but this doesn’t seem to be the source of the flies. What should we do?  Tracy

Dear Tracy: Your exterminator should know about drain flies. These pests breed in the soft, organic matter that coats the insides of drainpipes. To get rid of them, you must thoroughly remove the slimy residue in the pipes. This cannot be done with common drain cleaners, boiling water, or bleach. Instead, there are special products called “drain gels” that are specifically made for this type of drain cleaning. But before using drain gel, solid residues such as hair should be purged from the drains. For this, you should hire a plumber to snake out the lines.

Keep in mind, however, that drain flies can be breeding in other locations where there is rotting organic matter, such as moldy drywall or discarded food waste. In some cases, spillage from an open waste line under a home can provide the environment needed by drain flies.

To determine if the flies are originating in your drains, there is a tape test that you can do. For several consecutive nights, place a piece of duct tape across each of your drain openings, with the sticky side down. Do not cover the entire opening with the tape. Just run a strip of tape across the center of the orifice and leave the sides open. If the flies are breeding in the drains, some of them should be stuck to the tape in the morning. Hopefully, the drain is the source. Otherwise, you’ll have the job of searching for other places where breeding might be taking place.

Water Pressure Seems Too Low

Dear Barry: We bought our home less then a week ago. After moving in, we found the water pressure to be unacceptable. It takes forever to fill the bathtub, but the previous owners had said that they used it all the time. Why did our home inspector say nothing about low water pressure?  Lori

Dear Lori: People often mistake low water volume for low pressure. For example, it is possible to have normal or even high pressure and yet have weak flow at the faucets. This often occurs in older homes where corrosion in old galvanized steel pipes restricts the flow, regardless of pressure. Low flow can also be caused by a faulty valve or by water-saving devices in the faucets.

According to the Plumbing Code, water pressure must be at least 15 pounds per square inch (psi) and no more than 80 psi. You should ask your home inspector to come back and review this condition. He should take a pressure reading and evaluate the flow rate at the tub. You should also get an opinion from a licensed plumber.