For most households, drain flies are primarily a nuisance rather than a serious health threat.

They do not bite people in the way mosquitoes or biting flies do.

However, their presence can indicate that a drain or damp area needs cleaning or inspection.

It's therefore better to think of them as a clue rather than an immediate danger.

If you repeatedly see large numbers of them, particularly in multiple rooms, identifying and eliminating the breeding source is worthwhile.

Why Killing the Adults May Not Be Enough

This is where many people become frustrated.

You might spray the visible flies and think the problem has been solved.

Then, a few days later, more appear.

That's because the adults you see may only represent the final stage of a continuing life cycle.

Eggs and larvae can remain in the damp organic material inside a drain.

If that material remains undisturbed, new adults can emerge.

Therefore, source control is much more effective than simply killing the adult insects you can see.

How to Get Rid of Drain Flies

The first step is to identify where they're coming from.

Check the drains around which you see the most insects.

Pay particular attention to:

• Bathroom sinks
• Shower drains
• Bathtub drains
• Floor drains
• Kitchen sinks
• Laundry drains
• Rarely used drains

A useful clue is location.

If you consistently see drain flies around one sink but rarely elsewhere, that particular drain may be the source.

Clean the Drain Thoroughly

Physically removing organic buildup is an important part of controlling drain flies.

Depending on the fixture, this may involve cleaning the drain opening, removing hair and debris, and using an appropriate drain brush or cleaning method to remove the slimy material lining the pipe.

Simply pouring a random chemical down the drain is not necessarily the best solution.