06/20/2026
Happy Summer Solstice!
The Summer Solstice is tomorrow, June 21, at 3:24 AM CDT. It is the longest day of the year for the Northern hemisphere and marks the beginning of Astronomical Summer.
To start summer off right, I want to share one of my favorite activities: Water Bottle Rockets. The launcher is easy to build and your kids will enjoy launching the water bottles on a hot summer day!
Simple Water Bottle Rocket Launcher Instructions
Materials (All materials are available locally at Walmart and the lumberyard or hardware stores)
• 2 pieces of 1/2” PVC pipe. One shorter (18”-24”), one longer (3’-5’) exact lengths are up to you.
• 1 PVC 90° elbow
• 1 PVC end cap
• 1 valve stem (the kind used on bike/car tires)
• PVC primer and PVC cement/glue
• Teflon (plumber's) tape
• 1 O-ring or a rubber band
• Drill with a 1/2" drill bit
• Pliers (to hold the end cap steady while drilling)
• Bicycle pump
• An empty plastic water bottle (this is your "rocket"). You can add fins and a nose cone.
• Water
Build the Launcher
1. Clean the ends of both pieces with PVC primer.
2. Glue the elbow onto both pieces of pipe to join them at a 90° angle. This forms the main body of the launcher.
3. Drill a 1/2" hole in the end cap. Hold the cap steady with a pair of pliers while you drill.
4. Work the valve stem through the hole. Most valve stems have a flared end. Push that end through the hole and pull it through until it sits nice and snug.
5. Glue the end cap onto the short end of the elbow assembly, over the valve stem. That completes the main launcher.
6. Add a stop band. Stretch an O-ring (or a couple of rubber bands wrapped pretty tight) around the long tube, a little ways down from the top. This gives the bottle something to stop against when you slide it on and helps the bottle build up better pressure.
7. Wrap Teflon tape around that same spot, just to help seal things up.
8. Attach a bicycle pump to the valve stem. Any standard bike pump works.
Launch It
1. Add a little water to the bottle. Just a small amount, up to about the bottom groove of the bottle. Don't overfill it.
2. Tilt the launcher slightly so you don't dump the water straight down the tube.
3. Slide the empty water bottle (mouth-down) over the long tube until it rests against the rubber band/O-ring stop.
4. Grab a partner. One person holds the bottle steady while the other works the pump.
5. Pump it up to build pressure in the bottle then let it go!
Notes
• Pipe lengths are flexible. Adjust based on your kids' height.
• Smaller bicycle pumps are available and work great for younger children.
• For older kids, there are higher-powered launcher options if you want more height/distance. See links in the comments.
• As with any pressurized-air activity, keep faces and eyes away from the bottle opening, point the launcher away from people, and have an adult supervise with younger kids.
