Emergency water supply

Water is the most essential vital part of all survival resources. You can survive only 3 days "on average" without water. First and foremost lets go through the options.
1. Water Filters
Water filters like the Katadyn Pocket Water Filter are the best on the market prices range from $249.00 to $290.00 U.S.
Specifications
Filtration technology: Ceramic depth filtration (0.2 microns)
Effective against: Bacteria, protozoa, cysts, algae, silt, fungi. Reduces viruses attached to particles 0.2 microns or larger.
Output: Approximately 1 quart/liter per minute
Service life: Up to 13,000 gallons (50,000 liters)
Materials: Aluminum, stainless steel, POM, silicon, ceramic
Ideal use: Long term use for 1-4 people; backpacking and professional expeditions
Size: 10.2 x 2.7 inches (26 x 7 cm)
Weight: 1 lb. 5 oz.
A cheaper option is the Katadyn Mini water filter. Prices range from $69.00 to $99.00.Filtration technology: Ceramic depth filtration (0.2 microns)
Effective against: Bacteria, protozoa, cysts, algae, silt, fungi. Reduces viruses attached to 0.2 microns or larger particles.
Output: Approximately 0.5 quarts/liters per minute
Service life: 2,000 gallons (7000 liters)
Materials: POM, PC, silicon, ceramic
Ideal Use: short term use for 1-2 people; backpacking, biking and mountain climbing
Size: 7 x 2.8 x 1.6 inches (17.7 x 7 x 4 cm)
Weight: 8 ounces
Option #2.GI ISSUE WATER PURIFICATION TABLETS
Eliminates Giardia, Bacteria, Viruses, Removes Sediment. 1 or 2 Tables Good For 1 Quart or 1 Liter Of Water, Depending On Water Temperature.Water Purification. Chlor-Floc.
Option #3 For extended periods of time in your house in city environments.
It is recommended you store 1 gallon per person per day. That does no include showering drinking only.
55 gallon water drums with a manual pump. Price is around $70.00
A cheaper option is to find them on Craig's list. Make shure it is food grade.
Another cheaper option is Walmart. They sell water containers 5-6 gallon for around $8.00.
Option #4 Toilets and Water heaters make shure you boil the water.
Option #5 If you live in the country rule areas etc. Rivers Lakes Streams and ponds. Never drink the water out of any of these places without boiling or filtering the water.
The reason I mention Rule areas and not city areas it could be to dangerous in certain situations to leave your homeif you live in larger cities.