Hi my name is Chris.
Last october my grandmother passed away. I got many of her things, included about 20 house plants (about half of the different kinds). I held on to these plants. They have been growing very well since i've had them. A couple month's ago i brought a box of fruit back home to Edmonton from British Columbia. The box of fruit was infested with fruit flies ( I didnt realize until I had brought them into the house. Now every single plant's soil is infested with fruit flies.

Ive tried watering the plants with soapy water, This has kept control of the population, but not killed them. I've also tried backing the soil. It worked, but a stray fruit fly managed to repopulate.

Are there any secrets to wipe-out the population using anything that i might have around the house? Or do you know of a pesticide that i would be able to get from a local store?

PS... My grandmother had used tea from tea bags for fertilizer.

Most likely the soil is infested with eggs. They are attracted to wet soil.
You can use rubbing alcohol.

I just use house hold bug spray around the bottom of the plant and the soil.