ToughSF
The most accessible resource in space is not water, but dust. That is why technology to use it directly for propulsion, like this dust-plasma thruster, are so interesting: https://pubs.aip.org/aip/pop/article-abstract/14/5/053507/928004/Micropropulsion-in-space-via-dust-plasma-thruster Sadly this example exhibits abysmal 50-100s Isp by operating at 50 Volts.
