Figure 1: The launcher of water rocket. It was built with pipes alongside with pump as pressure controller on the front of it.
<a href="//commons.wikimedia.org/wiki/User:Joo_Nath" title="User:Joo Nath">Joo Nath</a>
CC BY 4.0
<span class="int-own-work" lang="en">Own work</span>