AWBRL for short. Just the other day I was watching a mythbusters episode where they made water bottle rocket launchers for a myth. It looked like so much fun and I went ahead and bought an aquapod for $35. It was great until it ruptured under normal use and no modifications! After that, I went to my local hardware store and bought a bunch of PVC fittings and a few other things so I could make my own with better reliability. This Instructable is about how to make a reliable, high performance, water bottle rocket launcher for cheap! 
Lets make It!
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Step 1: Safety

Picture of Safety
Now here is the important part. The safety information.
This is a pressure vessel. Pressure is dangerous. This bottle rocket launcher will utilize pressures up to 60psi. If you want to, you can add a safety valve but it would be easier to regulate the pressure with the source of air pressure. In my case, my portable air compressor. 
Make sure you use pressure rated PVC pipe. sch40 is recommended but I used another type rated to 260psi
As with any pressure vessel, be cautious around it at all times. 
ALL components MUST be pressure rated.
Do not use pressures over 60psi. There is no need. No increased performance at all!

Step 2: Parts

Picture of Parts
The total cost, without the cost of the schrader valve, was $25 and the Aquapod costed $35 and it offers far better peformance!
Here is the list of the parts: 
8x 10cm 15mm PVC pipes
20cm 15mm PVC pipe
3x 15mm 90 degree Elbow fittings
3x 15mm "T" fittings
15mm to 25mm coupler
4x 15mm PVC end caps
1 hose barb to threaded fitting.
1m (25 inches) of air compressor tubing
1x schrader valve (from bike tire)
2x hose clamps
10m of cord
15cm of thick wire
"O" ring to fit over the pipe

tyustar1 year ago
What size 'O' ring did you use?
baalajeek2 years ago
can this launcher hold a pressure of 80psi ?
dog digger (author)  baalajeek2 years ago
Depends on the type of pipe you are using. If you use sch40 pipe, the bottle will explode first. The bottles can handle 150psi when they are new and 120psi after a while but don't go past 90psi
jacobiscool2 years ago
soooooooooooooooooooooooooooooooooooooooooooooooooo gooddddddddddddddddddddddddddddddddddddddddddddddd
rimar20002 years ago
Very good work, dog digger!

About the energy, I am not sure but think a joule is a lot of it. Maybe you can ask an enginner or physicist.
dog digger (author)  rimar20002 years ago
Already have! (Lewster's brother, High distinction in physics competition)
stantonluke2 years ago
hello, i was wondering if you had a photo of the laucher with all parts on it and what kind of air compressor tubing was used
ljanus2 years ago
thanks that was very helpfull
ljanus2 years ago
hi, i would like to know what cord is used for,the size,and what the wire is used for?
dog digger (author)  ljanus2 years ago
The strings length is about 30ft (10m where I live. give or take)
dog digger (author)  ljanus2 years ago
They are both used for the triggering system. The wire is bent into shape and used as a retainer clip that holds the bottle in place. In the next step I had the small screwdriver through two of the four holes drilled in the 25mm to 15mm coupler. That is where the clip inserts into and the string is used to pull the clip out from a distance to launch the rocket
ljanus2 years ago
need to know as soon as possible!
lewster2 years ago
92 joules per second, or total?... coz 1 Joule per second equals 1 Watt.......Don't argue with Tom, top of Yr 11 Physics...
dog digger (author)  lewster2 years ago
the propelled flight was one second so, the answer to the question is Both!
lewster2 years ago
Jokes, it's really cool!
lewster2 years ago
yeah i know how to make it better..... It could be my air cannon!