In a serious emergency, you can’t rely on your municipal water supply. Terrorist attacks, earthquakes, flooding and other “issues” may make the water coming from your tap dangerous to come into contact with. Boiling is OK for microbial issues (if you are able to make a fire), but it does nothing for chemical contamination. The best thing to do is plan ahead and have a way to gather and store water from tap immediately, before there is a contamination issue.
If you want a good way to store water in an emergency, you can use foldable camping water jugs, 2 liter soda bottles, washed milk jugs, or even large ziplock bags. Of course, there is water in your hot water heater, but if it is a few years old, you’ll need to filter out the sediment. Another possibility is the WaterBOB. It reminds me of a small water bed bladder. Place it in your tub at the first sign of an emergency and fill it with water. It will hold 100 gallons of fresh water inside the tub and it has a handy siphon for filling bottles, etc. You may need to add a drop or two of bleach to keep the “critters” from growing over time. There are several versions of this product available with different names and specifications.
In the event you have to evacuate, your bug-out bag should have something to help you obtain potable water. Certainly you will have some water bottles in the bag, but you may need more, a lot more. Old fashioned Water Treatment Tablets are a staple in most hikers’ backpacks, but we have come a ways from that technology.The SteriPEN is a great alternative. Simply fill your water bottle with water and insert the pen into the top. Swirl it around with the pen on for a few minutes and it should be biologically safe. The UV light on the pen sterilizes any critters in the water. The drawbacks are that it does nothing for chemical contamination and it doesn’t clear up dirty water. Also, it’s battery powered, so if you are going to be using it a lot, bring extra batteries.
Probably the best alternative is a portable water filter. A unit like the Katadyn Vario Multi Flow Water Microfilter works well for a few people at a time. It fits easily into a bag, filters out most critters and many chemicals and can filter around 500 gallons before the filter needs to be changed. Buy a few extra filters and charcoal and you’ve got a good portable water filtration system for some time.
Water is your number one requirement after ensuring your safety. Food, blankets and bullets are all important, but without water you are gone in days, not weeks. So make some plans now.