also interesting enough

you can technically line a spaceship with a field bulkhead of water, provided you use hydrodynamics to circulate the water in the bulkhead containers to avoid expansion.

i digress. bulk water like this (at a width of several cm) can halt ionizing radiation by half. you can extend this with wider bulkhead containers for the ship. this in fact helps protect space vessels from ionizing radiation from solar flares etc

yes, nasa has tested the hell out of this