How to Get Rid of Drain Flies (Causes, DIY Fixes & Permanent Solutions)

Drain flies, also known as moth flies or sewer flies, are a common household nuisance, especially in bathrooms, kitchens, and laundry areas. While they’re not harmful, they can multiply quickly and usually indicate a deeper issue inside your drains.

If you’re wondering how to get rid of drain flies for good, this guide explains what causes them, which DIY methods actually work, and when professional plumbing is needed to stop them permanently.

What Are Drain Flies and Why Do They Appear?

Drain flies are small, fuzzy insects that thrive in damp environments. Unlike fruit flies, they don’t come from food left out on benches; they breed in organic buildup inside drains, floor wastes, and pipes.

They’re often a sign of:

• Slow or partially blocked drains
• Organic sludge lining pipe walls
• Poorly flowing or unused drains

Killing the flies alone won’t solve the problem unless the source is removed.

Common Causes of Drain Flies in Australian Homes

Drain flies are usually linked to one or more of the following issues:

• Grease, soap scum, and food residue in kitchen drains
• Hair and organic buildup in bathroom and shower drains
• Floor wastes that dry out or drain slowly
• Tree root intrusion in older sewer lines
• Cracked or poorly sloped pipes trapping stagnant water

In older Australian suburbs, clay pipes and mature trees can make drain fly issues more frequent.

How to Get Rid of Drain Flies (DIY Methods That Work)

If the infestation is minor, you may be able to reduce drain flies with the following DIY steps. These work best when the drain is slow but not fully blocked.

1. Clean the Drain Thoroughly

Use a stiff drain brush to scrub the inside of the drain opening and remove visible sludge. This is the most important step — surface cleaning alone is not enough.

2. Boiling Water Flush

Slowly pour boiling water down the drain in stages to help dissolve grease and organic residue. This can reduce breeding material.

3. Baking Soda and Vinegar Treatment

Pour half a cup of baking soda into the drain, followed by half a cup of vinegar. Allow it to fizz for 15–20 minutes, then flush with hot water.

4. Use a Plunger

For soft blockages, plunging can help dislodge buildup further down the pipe.

⚠️ Avoid chemical drain cleaners. They can damage pipes and rarely remove the organic sludge that drain flies feed on.

Room-Specific Drain Fly Tips

Bathroom & Shower Drains

• Remove hair and soap residue regularly
• Clean floor wastes and shower traps
• Ensure exhaust fans reduce moisture

Kitchen Drains

• Never pour grease or oil down the sink
• Use strainers to catch food scraps
• Flush drains with hot water regularly

Toilets & Floor Wastes

• Ensure floor drains aren’t drying out
• Flush unused drains with water periodically
  

Natural Remedies for Drain Flies

Natural methods can help reduce fly activity, but they won’t fix deeper drainage problems.

• Apple cider vinegar traps can catch adult flies
• Boiling water helps remove organic material
• Essential oil sprays may deter flies temporarily

These methods are best used alongside proper drain cleaning.

When DIY Methods Aren’t Enough

If drain flies keep returning, there’s usually an underlying plumbing issue.

You should contact a licensed plumber if:

• Flies return within days of cleaning
• Multiple drains are affected
• You notice slow drainage or gurgling sounds
• There are unpleasant sewer smells

Professional plumbers use CCTV drain inspections and high-pressure water jetting to remove organic buildup completely, something DIY methods can’t achieve.

How to Get Rid of Drain Flies Permanently

Permanent removal requires eliminating the breeding source inside your pipes.

Long-term solutions may include:

• Professional drain cleaning
• Clearing partial blockages
• Repairing damaged or sagging pipes
• Addressing tree root intrusion
• Improving drain ventilation or flow

Without fixing the underlying cause, drain flies will keep returning.

Preventing Drain Flies from Coming Back

Once the problem is resolved, prevention is key.

• Avoid pouring grease into sinks
• Use drain strainers in kitchens and bathrooms
• Flush unused drains regularly
• Schedule professional drain inspections every 1–2 years

Routine maintenance is far cheaper than emergency plumbing repairs. Maintaining clean drains and household hygiene is also recommended by NSW Health to reduce sanitation and pest risks.

Frequently Asked Questions

What are the early signs of drain flies?

Small flies near drains, slow drainage, gurgling noises, and unpleasant smells are common early indicators.

Are drain flies dangerous?

No, but they indicate unsanitary conditions inside your drainage system.

Will vinegar alone remove drain flies?

Vinegar can reduce adult flies, but it won’t remove the organic buildup causing the problem.

Can drain flies mean a blocked drain?

Yes. Drain flies often indicate partial blockages or stagnant water inside pipes.

Should I call a plumber for drain flies?

If DIY methods don’t work or the problem keeps returning, professional plumbing is recommended.

Need Help Getting Rid of Drain Flies?

If drain flies keep coming back, it’s often a sign of deeper pipe or drainage issues. Civic Plumbing provides professional drain cleaning, CCTV inspections, blocked drain services, and preventative maintenance across Sydney.

Call 0410 790 630 to book an inspection and stop drain flies at the source permanently.