How to Build a Water Rocket

Water rockets are plain simple fun that employs a simple physics concept to propel a miniature rocket structure into the air. The mechanism utilizes pressurized air to expel water from a nozzle at the water rocket’s base to launch it into the air from a simple launch pad. Water rockets usually takes a limited time to make and uses simple tools and components for assemblage.

Tools required

  • A Knife
  • Sandpaper
  • Saw
  • Epoxy glue

Materials required

  • 2 Soda bottles (ranging from 250 ml – 2 litres)
  • Tape
  • Inflator
  • Water
  • Plywood
  • Cardboard


  1. Take both bottle and use the knife to cut it into 3 pieces, the top, bottom and middle piece. Then draw out the shape of the fin into the wood and use the saw to cut it out. Smooth out the surface with sandpaper to be attached to the base of the bottle.
  2. Take the top piece that was just cut from the first bottle and place it on the bottom of the other bottle so both openings are facing opposite sides. Then use the insulating tape to attach the middle piece from the first bottle onto the second one.
  3. Then use the wood pieces that were cut out for the fins and join them with glue to the bottle with as the four empennages of the water rocket. Allow the glue to dry
  4. Paint the water rocket into whatever colour and design you wish and install a parachute to slow down the rocket to give a smoother landing.
  5. Pour 200 ml of water into the bottle and cap the rocket into the inflator for launching and place the rocket into the launch pad and pump air into the bottle in order for it to take off.
  6. Secure that the atmospheric pressure in the bottle reaches about 70 – 75% then launch the water rocket.

Tips and Warning

  • When pumping the air into the bottle stay away from the rocket and don’t pump too much air into it and be tolerant when handling it.
  • Because of the pressure placed on the bottles after each launch, you should replace the bottles after every other launch.
  • Never use the water rocket while indoors, it could hit something in the roof and cause damage and always use rocket outdoors away from buildings or objects that could be damaged in the process of using the water rocket.
  • A large nozzle allows the water out faster making the rocket go faster and higher but it loses all of the water at a faster rate, while smaller nozzles create less drag before the rocket takes off so it sustain the flight longer.
  • Utilize soap and mix it with water before pumping in the air, this can maximize the length of time the water rocket stays in the air.
  • If you wish, you can also make and install a cone nose for the water rocket to enhance the aerodynamics of the water rocket.

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