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How do I mix my pesticide and load my knapsack sprayer?

Review the advice below on how and where to mix your product, and how to load your product safely. See how to triple rinse emptied pesticide packs and how to avoid unwanted pesticide spills.

Before you start

Before you mix your pesticide product, make sure that you:​

  • are fit to spray
  • have advised your neighbors where and when you plan to spray
  • have checked and calibrated your knapsack sprayer
  • are spraying at the right time to control the pest and that the weather conditions are right for spraying
  • are wearing the right personal protective equipment (PPE) for mixing this product
  • know the total amount of pesticide product and water that you will need
  • know how much pesticide and water to load into each full knapsack sprayer and any part knapsack sprayer load. The spray mix calculator will help.

Check the scale on your tank

Look at the intervals to see which units are used (e.g liters of spray mix). The tank gauge on better knapsack sprayers will leave a 10% gap between the top of the gauge and the tank lid.

If the gauge on your sprayer reaches to the lid, do not fill the sprayer to the top as there is a risk that spray mix will leak from the filter cap and its vent. Instead leave a 10% gap between the top of the spray mix and the tank lid. For example, if the top mark is 16 L then a full load would be 14.4 L. If this means you will load less spray mix into your sprayer than you had planned, amend your calculations. The spray mix calculator may help.

Have your spill kit ready to use

Use a spill kit to clean up pesticide spills and drips when they happen. Whether you buy or make a spill kit, your spill kit must cope with the worst spill that can happen with the pesticide volumes under your care.

our spill kit must contain at least:

  • sand, sawdust, soil, clay, cat litter or vermiculite to absorb pesticide spills
  • shovel, broom and dustpan
  • strong bag for waste e.g. polluted sawdust or single use personal protective equipment
  • label and pen
  • strong plastic leak-proof drum or box able to contain the largest pesticide pack you have in your store
  • emergency telephone numbers.

Set up your spray area and mixing site

Review the video 'Setting up your spray area' to show you how to make your last minute checks of the spray site to ensure that it is safe to spray; or read the script.

Remember to:

  • have clean water nearby in case you are exposed to pesticides when mixing or spraying; and to wash any splashes or spills of pesticide from skin and eyes straight away
  • keep a supply of drinking water nearby so that you can drink regularly whilst spraying.
  • place warning signs around the spray area; keep them in place until the end of any re-entry period.

When mixing your pesticide product in the field, use a clean, flat surface that you can see while spraying and that is away from:

  • buildings in use
  • animals and people
  • water sources and drains.

Have ready:


  • your clean, checked and calibrated knapsack sprayer ready to spray
  • your mixing equipment; mixing tray, planning notes, pesticide container and label, portable product store, mixing tray, measuring cylinders or jugs.
  • your spill kit
  • enough clean water to make the spray mix and clean emptied pesticide containers. Also to clean your PPE when you have finished spraying.

If you do not have a mixing tray, use a sheet of plastic large enough to hold your knapsack sprayer, pesticide container and measuring jug. Lay your sheet in a suitable place. Create a small trough by building small banks of soil or sand around the edges of your sheet, and stretch the sheet over the small banks. Secure the sheet by covering the edge of the plastic sheet with more soil/sand.


Transport your pesticides from store to mixing site

Before moving the pesticide, check that you can spray as planned.

  • Wear impermeable gloves whilst carrying the pesticide container.
  • Keep the pesticide in its original pack in a locked box.
  • Carry the pesticide with care so that you do not drop or damage the box and spill the pesticide.
  • Take a route that is easy to use, and avoids surface water, homes and people.
  • Make sure that you can see the locked pesticide box whilst you spray.

Mixing your pesticide product

Cleaning empty pesticide packs

When cleaning your pesticide packs, you should wear the PPE that the label advises you to wear for mixing the product.

To triple rinse your empty plastic or metal pesticide packs:

  1. Pour water into the container until it is about 1/3rd full.
  2. Replace the cap securely.
  3. Upend then shake the container.
  4. Empty this liquid into the spray solution being mixed.
  5. Repeat steps 1-4 twice (i.e. rinse 3 times in total).


Rinsing your packs is best done when mixing your pesticide. Check your pesticide label for advice on how to dispose of pesticide packs and wrapping. If the label does not give advice ask your supplier and review this advice on how to recycle or dispose of your pesticide packs.