I keep all of my stones in the workshop and leave them to dry out. That way when I need ot flatten them out they are in the right condition to allow me to do so
Not really a hassel soaking a stone when I need to sharpen things, but I do have some small 3x1" versions of them that are left on the side of my workbench for touch ups when I don't want to wit the 5 mins it would take to soak a large stone
If you leave your stones wet or in the workshop to dry out, make sure they are insulated from the cold. Mine got frozen a couple of times this winter and so far most are ok, but I have had one stone begin to crumble from frost damage.
Antifreeze can be added to the water but I don't really wnat to do that since one of the reasons I like waterstones is coz they are clean
Also I don't want to have my hands in antifreeze!