Drain flies are found primarily in rooms or areas where there are drains such as kitchens, basements near floor drains, etc. Drain flies are small, 1/16 to 1/4 inch long, delicate and fuzzy. Their fuzzy wings make them easy to identify.
Inspect new houseplants before purchase. Choose plants that appear to be free of insects and disease, have new leaf or flower buds, and healthy foliage. Slipping the plant out of its container to look at the roots is recommended. Roots should be white or tan, fleshy (not brown and crumbly), be able to hold the soil together but not root-bound.
Start a compost pile by mixing together spent plants, kitchen scraps, fallen leaves, old mulch, and grass clippings. Shred your materials with a lawnmower, string trimmer, or machete to speed-up the breakdown process. Keep twigs, branches, and other woody materials out of the pile.