Water Rocket Launcher: Launching Your Homemade Water Rocket


Now that you’ve completed lesson 1 (building your water rocket) and lesson 2 (building your launcher) it’s time to send your rocket into the sky! This is definitely the most exciting part of the project!

Supplies You’ll Need

  • the water rocket you built (from lesson 2!)
  • the launcher you built (from lesson 3!)
  • one 2L pop bottle and cap (for holding your portable water supply!)
  • 300 ml dishwashing soap (optional, hand-wash-non-toxic type, makes your rocket fly higher!)
  • 1.7 liters of water (Not shown. This should be enough for 5 or 6 flights!)
supplies for the water rocket launcher

Tools You’ll Need For Your Water Rocket Launcher

  • a hand-powered bicycle air pump (for powering your rocket!)
  • water launcher pump

    This is definitely the most exciting part of the project. To build something yourself and then send it flying into the sky is a real thrill. Let’s start by mixing up a 2-liter bottle of soapy water for your rocket. Of course, you can use just plain water if you want, but the rocket flies higher and is much more visually appealing with the foam exhaust. Fill a 2-liter bottle 1/5 full with non-toxic hand-wash dish soap, then fill the rest of the bottle with water. In the photo you see our big industrial container of dish soap, but yours will probably be in a little squeeze bottle, with some fancy colouring in it.

    mixing soap with water for 20% mix

    This is how much dish soap to put in the bottle. It’s quite a lot, about 400 ml! It will give a 20% mix of soap to water in a 2-liter bottle.

    the soap is mixed with the water

    Once the dish soap is in the bottle, add water to fill the rest of the bottle almost to the top. Put the lid on the bottle and gently swirl it around to mix the soap and water without too much foaming.

    putting the cap on the soap mix

    Pour about 300 ml of water or water-soap mix into your rocket.

    pouring the soap rocket fuel into the rocket

    This is how full your rocket will be with the liquid in it.

    this is how full the rocket will be with rocket fuel

    Push the launcher’s cork into the mouth of the rocket bottle.

    putting the cork of the launcher into the rocket

    Set up the rocket pointing straight up in an open field with at least 200 feet (60 meters) of clearance (no buildings, cars, people or roads) on all sides. To help with the foaming of the water-soap mix, you can shake up the bottle first!

    pumping up the rocket it's getting full of suds

    Unroll the launcher tubing to its full 25-foot length and connect the bicycle air pump to the hose.

    connecting the bicycle pump to the water rocket launcher

    Close the compression lever on your pump connector so that it holds tightly onto your launcher hose.

    closing the pump connector on the launcher

    From 25 feet away from your rocket, pump until the rocket lifts off. It should take about 20 to 40 pumps depending on how far you pressed the cork into the rocket bottle.


    the rocket taking off into the skyNOW THAT YOUR WATER ROCKET WORKS, TRY LESSON 5: EXPERIMENTS TO TRY WITH YOUR HOMEMADE WATER ROCKET!Troubleshooting your water rocket launch