•
Add 2 drops chlorine for each liter of filtered water. Add 2 ml
(40 drops) of bleach for each 20 liters (5 gallons) of water.
•
Mix water well and wait 30 minutes before drinking.
•
Keep clean water container covered to avoid
recontamination.
•
Chlorinated water should have a slight chlorine odor. If it does
not, repeat the process and wait 15 minutes. Chlorine tablets
also work well and should be used according to manufac-
turer’s instructions. Chlorine solutions (household bleach) can
lose up to half of their strength when stored for just one year.
Chlorine evaporates out of treated water, so chlorine treat-
ment is always a temporary measure.
3. After initial 14 days: Water flow rate should be between .4-.8
liters (400-800 ml) per minute.
Note:
Water flow rate generally slows a little after a few days of
operation and may need readjusting on follow-up (see Filter Main-
tenance). The sand may also compact after a few days, requiring
additional sand to be added to the filter to maintain the paused
water depth of about at 5 cm (2 inches).
4. Store pre-filtered source water over night before adding it to the
filter. Sedimentation naturally occurs when pre-filtered source
water is stored overnight or for some hours. The more turbidity in
the water, the more hours necessary for sedimentation to occur.
The water begins to visibly clear as the suspended microbes and
contaminants settle and concentrate at the bottom of the
container. The water can then be slowly poured out of the con-
tainer into another container leaving many contaminants behind.
This process can dramatically improve the quality of the water
even before it is put into the filter. In cases of extreme water
sedimentation, repeat this process. This sedimentation process
can be significantly accelerated by adding a small amount of an
inexpensive flocculent such as alum to the water (3–6 ml [½–1
teaspoon] per 5 gallons of water).
5. Draw post-filtered water from the filter in “as-needed” quantities.
This practice reduces the amount of stored water, which in turn
reduces the opportunity for recontamination. Smaller quantities of
stored water are easier to protect than larger quantities.
Note:
Water that is retained in the filter overnight will generally be
the best water. This first water of the day is best for drinking.
8
Summary of Contents for BioSand
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