I have drain flies in the house, how to fix this?

Question

Noticed loads of little flies around the plugholes lately. Is this something I can fix myself or do I need a plumber?

Paul · Accepted Answer

You would be better getting a plumber in as you're waste pipes could be wrongly installed allowing access through the pipework

Greg · Answer

You can usually fix it yourself — pour boiling water and drain cleaner down plugholes daily for a few days, then scrub inside the drain trap.
Keep drains dry overnight and use a drain gel or enzyme cleaner to kill larvae.
If flies persist after a week, call a plumber to check for hidden leaks or blocked pipes.

James · Answer

Do it your self bi carbonate soda with white vinegar try this your self and for this it’s just your own time flies can get though drains and breed this time of year I hope this was helpful

Kennedy · Answer

Fruit flies are a common thing keep thew drain plugs in and cover all food you do need to check old onions , potatoes,that may have gone off that could be a good source for them they only live for a day but lay eggs like mad. Eventually they will die out without water or food.

Martin · Answer

Buy drain blaster kit from b and q or any plumbing centre

Stephen · Answer

I would just keep on top of ensuring the waste pipes are flushed with appropriate cleaners, it is very likely that it is due to the time of year and flies like to hang around these areas. Any other issues such as cracked pipes/leaks etc I would imagine would mean more noticeable issues than just the flies.

Thanks

Benjamin · Answer

There could be a blockage somewhere or a cracked pipe letting them inside on stack

Patrick · Answer

Is this a kitchen or bathroom sink? Are they fruit flies or houseflies? If it’s a shower or drain that’s not used often the u bend may have dried up. Pour some hot soapy water down it and it should be ok.

Patrick · Answer

Damage to drain normally the reason for the flies you will probably need a camera in the drain to assess and locate the damage

Asan · Answer

Step 1: Identify the source

Drain flies live in the slime layer that can build up inside drains.

Check: plugholes in the kitchen sink, bathroom sink, shower, or bath.

You might notice a musty or slightly sweet smell — that’s the larvae feeding on organic matter.

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Step 2: Clean the drains

1. Mechanical cleaning

Remove any visible debris from the plughole and drain cover.

Use a drain brush or an old toothbrush to scrub the inside of the drain as far as you can reach.

2. Chemical or natural cleaners

Pour a mixture of baking soda and vinegar down the drain:

50 g baking soda → drain

100 ml white vinegar → drain

Let it fizz for 15–30 minutes, then flush with boiling water.

This helps remove slime and eggs.

3. Repeat if necessary

You may need to repeat 2–3 times over several days to fully eliminate larvae.

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Step 3: Trap or kill adult flies

Place a sticky trap near the drain or make a simple trap with apple cider vinegar in a bowl with cling film and holes poked in the top.

This reduces the adult population while the drains are being treated.

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Step 4: Prevent recurrence

Regularly flush drains with boiling water.

Avoid letting food scraps, hair, or soap scum accumulate.

Keep plugholes covered when not in use if possible.

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When to call a plumber

If flies keep coming back despite thorough cleaning, it may indicate:

A blocked or slow drain

Broken or leaking pipe under the sink

A bigger infestation in the main sewer line

In that case, a plumber can inspect with a camera and resolve any structural or hidden drainage issues.

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💡 Bottom line: Most of the time, drain flies are DIY‑fixable with cleaning and prevention. A plumber is only needed for persistent or structural issues.

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If you want, I can give a simple 1-day DIY routine to get rid of these drain flies completely — something you can follow step by step. Do you want me to do that?

I have drain flies in the house, how to fix this?

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