How to make a boric acid liquid spray from powder

Boric acid is commonly used around the house to solve cleaning and pest control problems. Most commonly sold as a powder, boric acid easily dissolves in water to form a liquid spray. Boric acid is much less toxic that most commercial cleaners and can be used for pest control, cleaning, removing mildew and as a weed killer. Try using boric acid sprays around the house rather than buying commercial products. Not only is boric acid less toxic and more environmentally friendly, it is often less expensive as well.

Boric acid cockroach killer

Boil 1 litre (4 cups) of water on the hob. Pour the boiling water into the plastic bucket right away.

Stir in 250 ml (1 cup) of powdered boric acid. Stir the mixture vigorously with a spoon to dissolve the powder.

Fill an empty spray bottle with the boric acid and water mixture. Use a funnel for easy transfer and use caution so you don't burn yourself.

Spray the solution liberally in places where you have seen cockroaches. Target damp areas of the home with the spray as cockroaches prefer moist environments.

Boric acid ant killer

Combine 5 ml (1 tbsp) boric acid, 5 ml (1 tbsp) sugar and 120 ml (4 fl oz) of water in an empty spray bottle. Shake the bottle to thoroughly combine the ingredients.

Spray the mixture generously onto cotton wool balls. Place the cotton balls in areas where you have seen ants.

Spray the mixture directly on to the floor, counter or wherever the ants are visible if you prefer. Use caution when spraying the solution on to surfaces. Although boric acid is less toxic than many commercial insect killers, it is still harmful if swallowed or ingested in large doses. Clean the surfaces thoroughly after using boric acid.

Boric acid window cleaner

Combine 10 ml (2 tbsp) of powdered boric acid and 750 ml (3 cups) of water in an empty spray bottle. Shake the bottle vigorously to thoroughly mix the ingredients.

Spray the mixture directly on to windows or glass.

Use a dry paper towel to wipe the boric acid mixture from the surface.

Boric acid mildew remover

Dissolve 125 ml (1/2 cup) boric acid powder into a spray bottle with 500 ml (2 cups) of hot water. Shake the bottle to thoroughly combine the ingredients.

Spray the mixture directly on to mildew-stained fabric. Spray a generous amount of the mixture and allow it to soak into the fabric for several hours or until the mildew stain is gone.

Rinse the fabric with plain water to remove any residue from the boric acid solution.

Boric acid weed killer

Dissolve 280 g (10 oz) of powdered boric acid into 125 ml (1/2 cup) cup of warm water in a large bucket. Stir the mixture well until all of the boric acid powder has dissolved.

Add 9 litres (2 gallons) of water to the mixture. This will dilute the mixture appropriately.

Transfer the mixture to an empty spray bottle or a garden sprayer using a funnel. Apply the mixture to areas of the garden where there is a weed problem. Try to apply the mixture when no rain is expected for at least 48 hours. Only apply this mixture once a year for two consecutive years.


Keep boric acid out of reach of children and pets. Although it is less toxic than most commercial cleaners, it can still be dangerous if swallowed.

Wear rubber gloves when working with boric acid to protect your skin from irritation.

Things You'll Need

  • Water
  • Plastic bucket
  • Powered boric acid
  • Spoon
  • Empty spray bottles
  • 5 ml (1 tsp) sugar
  • Funnel
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About the Author

Kimbry Parker has been writing since 1998 and has published content on various websites. Parker has experience writing on a variety of topics such as health, parenting, home improvement and decorating. She is a graduate of Purdue University with a Bachelor of Arts in organizational communication.