As the project is evolving, somewhere in the future it might become desirable to switch from 10 liter condoms to bigger gas containers. The reason condoms are used up until now is because of the low (almost none) pressure required to inflate them with the gas, which is done by the water pushing back in to the bucket after the valve is opened. Once we scale up the collecting apparatus though, new tools are needed to pressurize the new gas containers.
A bicycle pump is something most people (at least in The Netherlands) have at home. By modifying the top cap (adding two o-rings in order to make it pressure-proof) and drilling a hole at the top of the chamber, where the incoming gas line will be connected, it becomes able to pressurize any container with either gas or air.