in ,

How to Mix Pesticides with Water

Sooner or later, almost everyone runs into a pest problem of one sort or another. Whether it’s ants and wasps invading your house, cockroaches in your kitchen, or caterpillars eating your food plants, pest species can cause lots of problems. Luckily, science has developed a wide range of different pesticides to deal with these creatures. And often, spraying a pesticide is the only way to take control.

Many pesticides aimed at the do-it-yourself market come ready to use. However, if you have a large or recurring pest problem, this can get expensive. Premixed pesticides in spray bottles and aerosol cans come with a healthy markup. Plus, all those containers create a lot of unnecessary waste.

Professionals in the pest control industry generally use concentrated pesticides that they then mix with water. This is far more cost-effective than buying ready-to-use products all the time. It also cuts down on waste and on the storage space needed.

bifen it concentrate

If you find yourself needing to spray pesticides on a semiregular basis, it’s a good idea to look into getting your hands on some concentrated pesticides that you can then mix yourself to save both time and waste.

However, using these concentrated products comes with responsibility. You need to be very careful when mixing pesticides the way the professionals do. Not only can pesticides be harmful to your health when improperly used, but they can also be very damaging to the environment.

Here’s how to get pesticide mixing right.

Benefits of Properly Mixing Your Pesticide

  • When it comes to pesticides, many people think that more is better but generally, the reverse is true. Overuse of pesticides can have extremely damaging effects on the environment and wipe out species that are actually beneficial. For instance, it’s speculated that the crash in honeybee populations is due to the overuse of pesticides to control other insects. Using too much pesticide and not mixing it properly can create far bigger problems than it solves and doesn’t kill pests any better.
  • Many pesticides are also harmful to human health. Often, pesticides are registered by government agencies based on a particular ratio. A pesticide that is safe at one mixing ratio may not be safe at another. Don’t take risks with your health or the health of your family by mixing pesticides incorrectly.
  • Pesticides either control insects or they don’t. If a pesticide kills bugs at a one percent concentration, for example, there’s no point making a two percent concentration and thinking it will work better. It won’t, and all you’ll be doing is wasting potentially expensive chemicals.
  • Mixing pesticides correctly the first time can save you time. Make sure you get the ratio right before you begin. Otherwise, if you apply too weak of a solution, you may have to repeat the procedure all over again, wasting both the chemical and the time you spent applying it. We have a DIY pesticide calculator you can use to help get the right mixture every time.


The first step to using pesticides both safely and efficiently is measuring correctly. Generally, pesticides will tell you how much water to add and how much coverage you can expect. To mix pesticides correctly, you’ll need to know how much area you need to cover and your spray tank size.

It’s important to get these figures right to prevent mixing too much pesticide. Often, concentrated pesticides, once mixed with water, quickly become inactive. Mixing too much will waste pesticide and give you a problem as to how to dispose of what you didn’t use. On the other hand, mixing too little means you’ll have to waste time mixing more. Generally, it’s better to err on the side of making too little than too much.

Also, when mixing pesticides, you should always do it in a well-ventilated area, preferably outside and away from other people. Some pesticides can release toxic fumes. Make sure you wear gloves and a respirator while mixing and applying pesticides. You should also wear sturdy boots and long sleeves and pants to protect yourself from splashes and spills.

Filling the Tank

Once you determine how much pesticide you’re going to need for the job in front of you and how much you should add to your tank, fill the tank with water up to the halfway mark. Then add the pesticide before adding the rest of the water. This will help the product mix thoroughly inside the tank.

Always follow the manufacturer’s instructions regarding how much pesticide to add. Often, the pesticide label will suggest different rates of mixing depending on the pest you’re targeting or the application method you’re using. Usually, they will give the amount of pesticide required for common tank sizes such as one gallon, two gallons, five gallons, and so on.

This can make it easier for you to get your amounts right. But if you have an unusual tank size or you’re only partially filling your tank to make sure you only use as much pesticide as you need, you may have to do some basic math to figure out how much pesticide you should add. If a gallon of water requires one ounce of a liquid pesticide, it’s not too difficult to figure out that half a gallon requires half an ounce. But the figures can sometimes be tricky, and it’s important to make sure you get them right. Our calculator can help.

Once you’ve added the pesticide to your tank, be careful while filling it up with water. The last thing you want to do is splash pesticide in areas you didn’t need it. You can avoid that by directing the stream of water at the side of the tank if possible. This stops the water from splashing. It can also help keep some pesticides more effective by stopping the water from falling onto them directly.

When filling with a hose, it’s also important to maintain an air gap between the bottom of the hose and the level of pesticide in the tank. If the end of the hose gets submerged in the pesticide, some of the chemical may backflow and enter the water supply, which is something you definitely want to avoid.

Many pesticides are especially harmful if they enter the water supply. Try to mix your pesticides well away from ponds or streams. If you have to mix pesticide near a water source, try to do it on the ground that slopes away from the water. It’s also a good idea to keep soap and water, paper towels, kitty litter, and other spill supplies nearby in case of an accident.

Pressurize the Tank

To spray efficiently, you’ll next need to pressurize the tank. Depending on the design of the tank you are using, there are a couple of ways to do this. The most basic sprayers work using a hand pump. Pumping the handle a few times will force air into the tank that will create pressure to drive the spray out when you pull the trigger. More expensive sprayers may use their own compressor, powered by a battery or even by gasoline.

sprayer hand pump

One useful feature to look for when shopping for a spray tank is a regulator. A regulator is a device that limits the amount of air that can be pumped into a spray tank and therefore limits the amount of pressure that builds up inside. Maintaining consistent pressure inside the tank helps to ensure that you spray at the same rate. Cheaper tanks without regulators mean you may end up spraying more pesticides in some areas than in others, which can waste chemicals and cause you to go through your pesticide a lot quicker than you need to.

Spraying the Pesticide

When spraying pesticide, consistency is key. Try to apply the pesticide evenly over the area that you need to treat. Maintaining consistent pressure will help you do that. Resist the urge to over-pressurize your spray tank. If the pressure is too high, it’s easy to spray into areas you don’t intend to, increasing the risk of environmental damage. Plus, spraying at too high a pressure can cause the pesticide to splashback onto you.

Also, take care not to overspray. With most pesticides, you don’t want to spray so much in one area that it creates runoff when the pesticide starts to flow over the ground. There are a few limited exceptions to this rule. For instance, when treating a fire ant hill in soil or a termite nest, you’ll need to use plenty of pesticides. But even in these cases, it’s better to stop spraying before the pesticide starts to run off and let it soak into the soil before spraying some more. This prevents wasting pesticide.

Spraying pesticide safely and effectively is a skill like any other. It can be tricky at first, but practice makes perfect. The important thing to get right from the start is to do it safely.

Wear personal protective equipment such as gloves and a mask. Follow the manufacturer’s instructions to the letter. Avoid splashes and spills.

A pesticide application done poorly can always be repeated, but damage to your health through improper pesticide use may be irreversible. Follow these simple steps for mixing and applying pesticide, and you’ll be able to stay safe while dealing with pest issues.

Want Help from a Pro?

Get a quick, easy, FREE, no obligation quote from a trusted exterminator.

Written by Wesley Wheeler

Wesley has over 10 years of residential and commercial pest control experience dealing with every kind of pest. He ran his own pest control company for 6 years and now shares his knowledge online.

Leave a Reply

Your email address will not be published.