How Do You Get Rid Of Drain Flies? | Express Drainage Surveys

You probably won’t be surprised to learn that drain flies are all too common a problem for homes and businesses in the UK. They are particularly a nuisance in bathrooms, kitchens and utility rooms, and although they’re relatively harmless, they can be persistent and unpleasant to have around.

The presence of drain flies also points to underlying issues that, if not addressed, will see this pest keep coming back. Many homeowners try surface-level solutions, only to find that drain flies come back a few days or weeks later.

So, how do you get rid of drain flies for good?

The short answer is that they live and breed inside your drainage system, feeding on organic matter. Minor infestations can sometimes be resolved with thorough cleaning, but persistent issues point to deeper issues, such as blocked or damaged drains, requiring professional inspection.

In this article we’re taking a closer look at these minuscule pests so that you can identify them, confirm the source and take the appropriate action to get rid of them.

What are drain flies?

Understanding your enemy is key to success. Drain flies, or as they are also known, moth flies and sewer flies, are small insects ranging between 2 and 5 millimetres in length. They can often be told apart from other flies due to their grey or brown fuzzy bodies and wings. This makes them look like a moth when they sit on your wall or tiles.

Despite having wings and “fly” in their name, drain flies aren’t particularly strong fliers. They take short, fluttering hops, and so often congregate around sinks, showers, baths and floor drains. You will notice that they are more active during the evenings and at night.

The reason drain flies love damp environments is that it helps them find organic sludge. This sludge is what they use to develop their larvae. The slime-like material from soap residue, grease, hair, food and other organic waste is the perfect bed for them to propagate in, which is why infestations appear suddenly and are hard to shift.

Drain flies vs fruit flies: How to tell the difference

Plenty of people mistake the drain fly for a fruit fly, but if you don’t learn to tell the two apart, you might make things worse when attempting to deal with them.

Drain flies, as mentioned, are small, furry moth-like insects attracted to your sinks, showers and drains, not food and fruit.

Fruit flies are small-bodied, often tan or orange in colour and will definitely be attracted to your fruit bowl. They are much better fliers and typically only appear in the warmer months.

What causes drain flies in UK homes?

It’s not necessarily poor hygiene which causes drain flies. You could have a well-maintained home and still experience an infestation if the conditions inside your drains allow any organic material to build up.

Common causes of drain fly infestation include:

Organic build-up in drains: This is the top attraction for drain flies, and it’s down to a gradual accumulation of substances over time, creating that breeding ground out of sight.
Slow or partially blocked drains: Water and debris sitting around in drains help to retain damp, making it ideal for larvae to develop.
Unused drains: If you have a guest bathroom or utility room sinks, these can dry out, accumulate stagnant organic material and draw the attention of drain flies.
Older drainage systems: For ageing underground drainage systems, there is an increased risk of blockages, and they potentially don’t meet modern standards. This is the ideal place for organic matter to build up.
Damaged or cracked pipes: Any cracked, displaced or collapsed portions of a drainage system can trap moisture and encourage drain fly infestations.

Are drain flies dangerous to health?

Drain flies do not bite, so they aren’t considered dangerous in a direct sense. However, you still shouldn’t ignore them.

Think of drain flies as an indicator of underlying hygiene issues. Since they breed in drains, they carry bacteria from your waste pipes onto any nearby surfaces. They point to standing water and composting organic material, so it should be treated as a signal for change.

You should also consider their presence as a symptom of deeper drainage problems if your home is always kept clean and fresh, as it could mean there is a blockage or structural issue somewhere in the pipework.

How do I know drain flies are coming from my drains?

You can’t really know without sitting and staring at your drains, and no one has time for that. Instead, you can try the tape test for confirmation.

This is a simple test, where you place clear sticky tape over the drain opening at night, placing the sticky side down over the hole. Leave this in place and check the tape in the morning. If you have flies stuck to the underside of the tape, then you know they are coming from inside the drain rather than from somewhere else in the home.

You can try this test with multiple drains if you’re unsure, as there may be more than one point at which they’re entering.

How to get rid of drain flies for good

There are a few DIY methods you can try to rid your home of drain flies before calling on professionals to tackle deeper drainage issues:

Thoroughly clean your drains: This means removing covers and scrubbing away as much residue from inside the drains. You should then pour boiling water down to loosen and clear the system further along.
Deploy drain cleaners: Some basic drain cleaning products you can buy in the supermarket may help to break down light organic matter, but they can be limited unless used consistently.
Try drain snakes or brushes: Mechanical tools could help to dislodge debris deeper in the pipework, but only attempt this if you have experience working with drains, as you could cause damage.

If you’ve tried all of this and drain flies keep coming back, or if multiple drains are affected, you potentially have a deeper issue. The best way to get to the bottom of this and to get rid of drain flies for good is to engage with drainage professionals.

At Express Drainage Surveys, we carry out CCTV drain surveys to establish any issues deeper within your drainage system, before recommending any cleaning and repairs. You can read more about some of our key services for clearing drains below:

Don’t put up with persistent drain fly problems – contact our expert team today and we’ll be happy to arrange an appointment to get to the heart of the issue and put your mind at ease.