United States
            Environmental Protection   Office of Water                EPA 810/F 93 OQ2
            Agency              (WH-550)                    July 1993

                           DRINKING  WATER

          There are two general methods  by which small quantities of water can
     be effectively disinfected.  One method is by boiling. It is the most positive
     method by which water can be made  bacterially safe to drink.  Another
     method is chemical treatment.  If applied with care, certain chemicals will
     make most waters free of harmful or pathogenic organisms.

          When the home water supply system is interrupted by natural or other
     forms of disaster, limited amounts of water may be obtained by draining the
     hot water tank or melting ice cubes. In most cases,  ground water is
     generally the preferred source of drinking water. If it is not available and
     surface water must be used, avoid sources containing floating material or
     water with a dark color or an odor.

         When  emergency disinfection is  necessary, the physical condition of
     the water must be considered. The degree of disinfection will be reduced in
     water that is clouded.  Murky or colored water should be filtered through
     clean cloths or allowed to settle, and the clean water drawn off before
     disinfection.  Water prepared for disinfection should be stored only in clean,
     tightly  covered, containers not subject to corrosion.

    BOILING.        Vigorous boiling for three minutes will kill any disease-
                    causing microorganisms present in water.  The flat taste of
                    boiled water can be improved by pouring it back and forth
                    from one container into another (called aeration), by
                    allowing it to stand for a few hours, or by adding a small
                    pinch of salt for each quart of water boiled.

    CHEMICAL      When boiling is not practical, chemical disinfection  should
    TREATMENT    be used. The two chemicals commonly used are chlorine
                    and  iodine.

CHLORINE       CHLORINE BLEACH.  Common household bleach contains
                 a chlorine compound that will disinfect water.  The
                 procedure to be followed is usually written on the label.
                 When the necessary procedure is not given, one should
                 find the percentage of available chlorine on the label and
                 use the information in the following tabulation as a guide.
                                       Drops per
                 Available Chlorine1         quart of
                                       clear water2

                      1%                    To""
                      __                   _

                      __                  .
                 1 If strength is unknown, add 10 drops per quart of water.
                 2 Double amount for cloudy or colored water.

                 The treated water should be mixed thoroughly and allowed
                 to stand for 30 minutes.  The water should have a slight
                 chlorine  odor; if not, repeat the dosage and allow the
                 water to stand for an additional 15 minutes.  If the treated
                 water has too strong a chlorine taste, it can be made more
                 pleasing by allowing the water to stand exposed to the air
                 for a few hours or by pouring it from one clean container
                 to another several times.

                 GRANULAR CALCIUM HYPOCHLORITE.  Add and dissolve
                 one heaping teaspoon of high-test granular  calcium
                 hypochlorite (approximately 1/4 ounce) for  each  2 gallons
                 of water.  This mixture  will produce a stock chlorine
                 solution  of approximately 500  mg/L,  since the calcium
                 hypochlorite has an available chlorine equal to 70 percent
                 of its weight.   To disinfect water, add the chlorine solution
                 in the ratio of one part of chlorine solution to each 100
                 parts of water to be treated. This is  roughly equal to
                 adding  1  pint  (16 oz.) of stock chlorine solution to each
                 12.5 gallons of water to be disinfected.  To remove any
                 objectionable  chlorine odor, aerate the  water as described

                  CHLORINE TABLETS.  Chlorine tables containing the
                  necessary dosage for drinking water disinfection can be
                  purchased in a commercially prepared form.  These tablets
                  are .variable from drug and sporting goods stores and
                  should be used as stated in the instructions.  When
                  instructions are not available, use one tablet for each quart
                  of water to be purified.                           q

 IOD,NE          ™CTU"E OF IOD'"e- Common household iodine from
                 the med.c.ne chest or first aid kit may be used to disinfect
                 water.  Add five drops of 2 percent United States
                 Pharmacopeia (U.S.P.) tincture of iodine to each quart of
                 clear water.  For cloudy water add ten  drops and let the
                 solution  stand for a least 30 minutes.

                 IODINE TABLETS.  Commercially prepared iodine tablets
                 contaming the necessary dosage for drinking water
                 disinfection can be purchased at drug and sporting goods
                 stores.  They should be used as stated. When instructions
                 are not available, use one tablet for each quart of water to
                 be purified.

PROPERL Y DISINFECTED                      ^UULD BE