Lady ... when it comes to water purification, hard to beat plain old boiling, especially when your in a residence and can set it aside to cool off. And you don't have to leave it boilng for for a set period of time, just bringing it to a boil will suffice to kill any and all pathogens. Here the cost is only that of the fuel or electric used to heat the water. The next best method in my experience, dating back to years ago in the military was iodine. For example, if you were to use povidone iodine (Betadine), four drops to a quart or liter of water will do the job. If the water is clear, let it set for maybe 30 minutes before use. And the iodine taste can be countered with a drop of liquid vitiman C - Of course, you don't want to be messing with iodine if your pregnant or have a thyroid condition. I know there have been a zillion filtration systems that have came out on the market in past few years, but there's a cost factor to them.
I see Cabela's offer an MSR ceramic filter that's toted as a high performer; also they have other microfiltering systems. I carry in my fishing vest a microfilter straw just in case I get somewhere "up-the-river" and need a drink real bad NOW. Also carry one of those "Brita" water filtering pitchers in the camper, which is not for water purification, of course, but does a fair job of removing chlorine taste and has even removed a respectable degree of rust removal from well water (with a hand pump) at a state forest campground that we like to frequent.

Again, boiling is my favorite and a sure bet to get the job done. Chemical and filtration will cost more, just depending on how precise you want to go.

Dale

The MSR or other ceramic-filter type devices are the only way to go, IMHO. You won't waste the fuel you need to cook food boiling all your water and you can clean and reuse the filter thousands of times. The US military uses the MSR ceramic types and they are the experts.

boiling, iodine, household bleach (Sodium hypochlorite), filter or miox.

Can Clorox® Regular-Bleach be used to disinfect water?
Emergency Disinfection: When boiling water is not practical, water can be made potable by using Clorox® Regular-Bleach. Before the addition of the disinfectant, remove all suspended material by filtration or by allowing it to settle to the bottom. Decant the clarified contaminated water to a clean container and add 8 drops of Clorox® Regular-Bleach to one gallon of water (2 drops to 1 quart). Allow the treated water to stand for 30 minutes. Properly treated water should have a slight chlorine odor. If not, repeat dosage and allow water to stand an additional 15 minutes. The treated water can then be made palatable by pouring it between clean containers for several times. For cloudy water, use 16 drops of Clorox® Regular-Bleach per gallon of water (4 drops to 1 quart). If no chlorine odor is apparent after 30 minutes, repeat dosage and wait an additional 15 minutes. Do not use scented or Splash-less Clorox® Bleaches for this purpose.

http://www.clorox.com/solutions_reg_bleach_faq.html

bleach is nice to have in an emergency since it can be used to sterilize surfaces of mold & bacteria since they will thrive after such a flood. you can also sterilize your water containers before you fill them, something people overlook when purifying water.

this calculator is pretty useless since all it does is multiply # of gallons by 8 drops of bleach and factors condition of water to double dosage. all this is pretty basic. but the information on the page is pretty thorough.

i have a filter & the msr miox water purifier. the miox is nice because you can treat large volumes of water. it's about the size of a sharpie marker. it uses batteries & salt to create a water purifying oxidant. pretty neat. it's expensive about $120, but it'll fit in your pocket.

Here is a link that might be useful: emergency water purification calculator

I bought the Berkey Light. Good for car camping, home use and emergencies as well. A bit expensive at $200 but it should pay for itself. It'll be delivered in a couple of days - sure hope I made a good investment.

The Berkey is one of the reusable ceramic filter types. This is the best technology out there.

Make sure you get the Black berkeys over the ceramics though. They filter out more contaminants.

Here is a link that might be useful: Berkey Light Filter

i heard berkeys has one of the best ceramic filtering system.

i heard berkeys has one of the best ceramic filtering system thanks

Industrial water reverse osmosis....the kind hotels use, get the water as it enters the home