There is algae in the potable water tanks on military ships. I am pretty sure it just filters the water.
I think you're right. The water on my boat tasted like crap for the first few months after we were in the yards and got our potable tanks all cleaned out and painted up all spiffy. Once the algae gets a chance to grow in there it tastes like it's supposed to.
It seems like it would be prudent to have a water purifier, even though they're pretty expensive, so I'm looking them over online. It seems pretty likely that if we got tsunami'ed, most of the accessible water would be contaminated with sea water. Just wondering, are there any practical water purifiers out there that can also desalinate water, or would I be better off with a big bucket, small bucket, and Saran-Wrap setup combined with a sterilizer like the SteriPen? I'm having a pretty difficult time finding anything useful for making potable water out of sea water. The closest thing I found was some kind of straw thing-a-ma-jig that had an RO filter in it, and somehow used sugar to help get rid of the salt. Bottom line is, it's not sustainable, unless you're willing to buy a ton of them, plus it makes the water into some sort of sugary drink.
I guess if I can't find anything, I'll combine some storage with a SteriPen, and if the water's contaminated with salt, then I guess my kid will get a head start on her science fair project with a DIY solar still. Or, I could buy
this thing.