Emergency water storage

For a variety of reasons, it seems like Jared and I should be getting serious about emergency preparedness. We have some food storage and I plan to continue working on that. One thing that has always weighed on my mind is water storage. Particularly in our small apartment, there is no feasible way to store more than a 72-hours' supply of water. That's a start, but I still get nervous that it might not be enough. Not only that, but it would be nice to have enough water to share with those who might be truly desperate. I don't want to be the one sitting by sipping water while the neighbor's baby dehydrates.

So for a while I've wondered how to address this water storage issue. Although we will probably have more room in the near future, there are still limitations with traditional water storage, including the possibility of bacteria entering into water stored for lengthy periods, and transportation issues should an evacuation be necessary.

I have been looking at water filters as a possible solution. In a disaster, they say that water is almost always available, but usually from contaminated sources such as compromised plumbing, pools, streams, standing flood water, etc. The issue is finding a feasible way to treat that water. Good portable filters will address bacteria and really expensive ones will filter out viruses. Pump filters do have their own limitations as far as the potential for clogging and can't be used in very dirty water, so water has to be extensively pre-filtered for large contaminants. They do have very high output, though.

After doing a lot of reading and researching, I am seriously considering purchasing one of these. The X-Pack is a military-grade forward osmosis system which produces about a 1.5 liters of purified water every eight hours for up to ten days or longer with supplemental osmosis packs -- in short, 5.5 liters a day for 10 days or so. Because it relies on a syrup solution to create the osmosis, the water comes out slightly sugary, like a sports drink. However, it can be used in even the most filthy water, and filters bacteria, viruses, and some heavy metals. It's not super-cheap, but it's not prohibitively expensive, and definitely solves the transportation/volume issue for scenarios where water is needed for more than a couple of days or away from home.

The one drawback I see is that it's a relatively small volume of water for our family of three, especially if we were in a situation where we were exerting a lot of energy or doing heavy manual labor, so I would still want to keep at least a 72-hour supply of portable, purified water and have this as a backup in our 72-hour kits. I think it's enough to get by on or to extend our supply enough to share a little.

I'd be curious to hear how others are addressing the emergency water storage issue.

Update: I just read the FAQs on the manufacturer's site and they say there is little to no risk of membrane rupture past the 10-day recommended usage. According to them, the most probable issue after 10 days is that bacteria from the clean side of the membrane (from ordinary handling or contact with your mouth) will start to flourish. However, that type of bacteria is normally not particularly harmful, and certainly not as harmful as drinking untreated water, if that is the alternative. I am getting more and more impressed with this product. If I had the money, I'd be tempted to rush right out and get the HydroWell.