Every summer in the UK, heatwaves bring sunshine, barbecues, and longer days — but also an invasion of flies. These buzzing intruders find their way into homes, kitchens, and gardens, frustrating homeowners everywhere. People often ask: How to Keep Flies Out of the House without resorting to harsh sprays or toxic chemicals? Luckily, there are simple, affordable solutions that can help protect your home from these pests.
Why Flies Are Such a Problem Indoors
Flies aren’t just irritating — they pose real health risks. By feeding on rubbish, waste, and decaying matter, houseflies pick up bacteria, parasites, and even viruses. Once inside, they land on food, kitchen counters, and surfaces, contaminating everything in their path. This is why knowing how to keep flies out of the house is not only about peace of mind but also about safeguarding your family’s health.
Houseflies have complex compound eyes, giving them sharp vision in multiple directions. This makes them extremely responsive to movement and changes in light. Using this against them is at the heart of one of the most surprising and effective natural deterrents.
The Plastic Bag and Coin Trick
One of the most popular methods for keeping flies out of the house is the simple water bag trick. All you need is:
- A clear ziplock bag
- Clean water
- A few coins (or copper pennies)
Fill the bag halfway with water, drop the coins inside, and hang it near windows, porches, or doors. As sunlight hits the bag, it creates reflections and refractions that disorient flies. Because flies’ eyes are sensitive to changes in light patterns, the distorted visuals from the bag trick them into staying away.
As HowStuffWorks explains, “Flies have many small lenses in their eyes that are sensitive to light changes, and the distorted light from the bag is thought to disrupt their vision.” In other words, this low-tech solution provides an easy answer to anyone searching for how to keep flies out of the house without chemicals or complicated traps.
Used Around the World to Keep Flies Away
The water bag method isn’t new. Across the globe, restaurants, market stalls, and outdoor eateries have relied on this trick to keep pests away from food. You may have even seen plastic bags hanging in barns, gardens, or porches during your holidays abroad.
There are variations on the technique — some people add shiny tinfoil instead of coins, while others insist copper pennies work best. A few businesses even sell ready-made water bags designed specifically to repel flies. But whatever version you use, the principle remains the same: bending light in a way that confuses and deters houseflies.
Social Media Proves Its Success
In recent years, social media platforms like TikTok have helped spread this old trick to a wider audience. Videos show homeowners hanging water bags by their doors and windows, with many claiming dramatic improvements.
One user shared: “Don’t know why, but I’ve been doing it for years. I lay the bags flat on the table where the food is and no fly in sight.”
Another simply commented: “That’s wild — it really works!”
The viral success of this hack shows that more and more people are discovering how to keep flies out of the house with simple, natural solutions.
Other Tips for Keeping Flies Out of the House
While the plastic bag trick is powerful, it works best when combined with good habits and preventive measures:
- Keep bins sealed – flies are attracted to rubbish, so always close lids tightly.
- Clean surfaces regularly – crumbs, spills, and food scraps draw flies indoors.
- Use natural deterrents – herbs like basil, lavender, and mint can help repel flies.
- Install screens on windows and doors – physical barriers are one of the most reliable ways of keeping flies out of the house.
By combining these methods, you can reduce fly invasions significantly, especially during the warmer months.
Final Thoughts
Flies may be an unavoidable part of summer, but with the right approach, you don’t have to share your home with them. If you’ve been searching for how to keep flies out of the house, try the water bag trick alongside other simple steps. Affordable, eco-friendly, and proven effective by people worldwide, it’s one of the easiest ways to stop flies before they become a problem.
So next time the buzzing begins, remember: a bag of water and a few coins could be all you need to keep flies out of house and enjoy a fly-free home.
