If you're battling drain flies, you know what an annoyance they can be. They usually come from floor drains, but can also find their way into other infrequently used drains.Fortunately, there are several effective ways of getting rid of drain flies.
Roto-Rooter, America's leading provider of plumbing & drain services, recommends the following methods of killing drain flies and their larvae.
First, pour 1/2 gallon of water through the drain. If the water drains away quickly, that means the drain is functioning properly. If possible, pour in a panful of very hot water to kill larvae. (Remember that boiling water can cause some surface materials to crack).
Next, pour in a cup of white vinegar. This should finish off the larve stuck to the inside of the pipe. Some people recommend bleach, but bleach is caustic and can be dangerous. If you use bleach, do not mix it with the vinegar or you'll create dangerous chlorine gas. Take the cap off the bleach bottle and pour bleach into the cap. Then pour the capful of bleach into the drain. That's more than enough bleach to kill insects and their larvae inside the pipe.
Then pour the capful of bleach into the drain. That's more than enough bleach to kill insects and their larvae inside the pipe.
Besides white vinegar or bleach, several other household items can also kill drain flies. Just be careful not to mix any of these concoctions or you might endanger yourself. Pour in 1/2 cup of salt and 1/2 cup of baking soda plus a cup of white vinegar. Allow it to work its magic overnight then flush the drain with hot or boiling water the next morning. This will sanitize the drain and kill the flies and their eggs.
Floor drain odors are commonplace in homes and businesses. And many homeowners complain about drain flies and other bugs that seem to gain access to their homes from floor drains. Most homeowners are unaware that the remedy for both of these problems is simple. This is the part of the floor drain that you can't see. Water passes through this U-shaped pipe called a P-trap. It's a lot like the traps you find beneath sinks. This bend in the pipe is designed to trap water and create a water barrier that prevents sewer gases and insects from coming through the pipe into your home. Pour a half gallon of water into the trap to fill it. This will stop the odors from coming through. You may also add a cup of white vinegar to kill insect larvae and slow evaporation. Some homeowners pour in bleach to do the same but bleach is caustic and can be dangerous. If you pour in bleach, use it sparingly and wear eye protection. No more than a capful of bleach is needed to kill insect larvae.