Purifying Household Water
Use the methods described below only to make water safe from bacteria or viruses. Do not drink water you think may contain chemicals, oils, poisonous substances, sewage, or other contaminants,.


PO Box 47890
Olympia, WA 98504-
7890

Web Site:
www.doh.wa.gov

360-236-4027
(800) 525-0127
Store water safely
Store one gallon of water per person per day.
Store at least a three-day supply of water per
person.
Collect the water from a safe supply.
Thoroughly washed plastic containers such
as soft drink bottles are best. You can also
purchase food-grade plastic buckets or
drums.
Seal water containers tightly, label with date,
and store in a cool, dark place.
Replace water every six months.
Never reuse a container that held toxic
materials such as pesticides, solvents,
chemicals, oil or antifreeze.
Water purification
There are two good ways to treat water: boiling
and adding bleach. If tap water is unsafe
because of surface water contamination (from
floods, streams or lakes), boiling is the best
method.
Filter cloudy water before boiling or adding
bleach.
Filter water using coffee filters, paper
towels, cheese cloth or a cotton plug in a
funnel.
Boiling
Boiling is the safest way to purify water.
Bring the water to a rolling boil for one
minute.
Let the water cool before drinking.
Purifying by adding liquid chlorine bleach
If you can’t boil water, treat it by adding
liquid household bleach, such as CloroxTM
or PurexTM. Household bleach is between 5
percent and 6 percent chlorine. Do not use
bleach that contains perfume, dye or other
additives. Be sure to read the label.
Place the water (filtered, if necessary) in a
clean container. Add the amount of bleach
shown in the table below.
Mix well and allow to stand for at least 30
minutes before using (60 minutes if the
water is cloudy or very cold).

Treating Water with a 5-6 Percent Liquid Chlorine Bleach Solution
Volume of water to be treated Treating clear/cloudy water
Bleach solution to add Treating very cold, or surface water Bleach solution to add
1 quart/1 liter 3 drops 5 drops
1⁄2 gallon/2 quarts/1 liter 5 drops 10 drops
1 gallon 1/8 tsp 1⁄4 tsp
5 gallons 1⁄2 tsp 1 tsp
10 gallons 1 tsp 2 tsp