What are Drain Flies?

Drain flies are also known as sewer flies, moth flies or sink flies, are about the size of gnats and fruit flies—measuring ¼” in size— Drain flies can be identified by their color, typically ranging between pale gray to black and their small, moth-like wings and round, fuzzy bodies.

Where Do Drain Flies Come From?

Drain flies enjoy stagnant water that collects even small amounts of bacteria and sewage, so they are often found in and around:

  • Kitchen and outdoor sinks
  • Shower and bathtub drains
  • Basement sinks (especially those that go unused for some time)
  • Sewers
  • Septic tanks
  • Soil that contains sewage

One common denominator among all of these places is low, stagnant water. Drain flies can lay eggs in the film that forms on the inside of pipes and drains when water pools and collects sewage. For this reason, drain flies may also be attracted to:

  • Wet mops and buckets
  • Compost piles
  • Storm drains with standing water
  • Wet areas around the garbage, birdbaths, or barns

Drain flies have a lifespan of between 8 and 24 days but can lay and hatch up to 300 eggs in just 48 hours, so it’s important to get ahead of the problem before they have a chance to spread through your pipes.

How to get rid of Drain Flies

Drain flies are not harmful to humans. Adult sewer flies do not bite or sting and do not require blood for egg development. Though drain flies consume and live-in sewage and bacteria, they are not disease-carrying insects. Your are an ideal place for drain flies to thrive and reproduce. Drain flies can also reproduce quickly, spreading nests throughout your pipes that can be costly to clear out if left unchecked. So how do you get rid of drain flies?

Although there are chemical routes you can take and depending on the size of the infestation might be better suited for, we will be looking at natural ways of getting rid of and removing drain flies.

  • Method 1 Boiling Water – The simplest method to deal with drain flies is to carefully pour bowling water down your drains once or twice a day for a week
  • Method 2 Baking Soda, Salt & Vinegar – Mixing these items to create a cleaning solution and pour down your drain overnight. The baking soda expands with the vinegar, reaching more areas than just boiling water. After letting the solution sit overnight, flush out the pipe with boiling water.
  • Method 3 Soap, Water, Sugar & Vinegar – Add a few drops of dish soap to a bowl of water, sugar, and apple cider vinegar. Leave the bowl out for a few days close to the drain to attract the drain flies to the sweet solution. The thickness of the added soap will trap the flies in the water. Keep in mind that you may need to repeat the process after the remaining colony hatches, ultimately stopping their lifecycle.
  • Method 4 Hydro Jetting – Before contacting pest control and having to add pesticides or hash chemicals down your drains, consider contacting a plumbing company and requesting hydro jetting. This is the process of cleaning your sewer and drains using high pressure water. This will process is not only natural, environmentally friendly and non-evasive, but is an effective way of eliminating drain flies, larvae/eggs and removing the conditions that made it ideal for them to breed and prosper.

How to Prevent Drain Flies?

Drain flies breed in areas that are moist and have a lot of organic debris. They can breed in overflow cuts, sinks and tubs, sump pump pits, and sewers. Outdoors, they can breed in air conditioners, birdbaths, shallow stagnant pools of water, and standing water. Adult drain flies can enter homes from the drain pipe openings of kitchen sinks, bathtubs, and toilet sinks and can rest indoors on the walls.

Maintain a healthy septic system.

Always keep an eye out for early signs of an infestation, even if you just see a few drain flies. Taking precautionary steps to check and treat a possible problem is essential.
If you allow the standing water in your pipes or property to go unchecked, drain flies will rarely go away on their own. Warm homes even allow drain flies to live throughout the winter. Be sure to take preventative measures after flushing out your system to keep drain flies in check.
However, if these DIY efforts fail to keep drain flies from coming back, we recommend speaking with a specialist to make sure you are treating the whole issue.