[Calvin Locke]

One of the space books I've read said one astronaut on the ISS would sleep in the water storage room, figuring the containers of water would help reduce his radiation exposure.

I've also read that aluminum, when struck by a high-energy particle is easily capable of losing and loosing a neutron to go plowing into whatever is in the way, such as say, DNA.

[struggle]

Spacesuits are eventually going to have circulating water in suits for this reason. It auto-controls temperature, it protects against radiation, and place a water-activated polymer on the outside and if the suit is punctured by a microsatellite or mistake the suit can autoseal from the leakage of water.

[Nuc 1.1]

Approximately two feet of water is a tenth thickness for gamma. That is it will reduce the dose to 1/10th of the previous dose.