Home Water Storage
Kelly A. Reynolds, Ph.D.
Home water storage is a practice
many believe is essential in the event of an emergency, when water
supplies might be unavailable or tainted. We need only look to the
stockpiling craze of last December fed by Y2K fears for an example.
Unfortunately, stocking a safe backup water supply isn't as easy
as filling containers and storing them on the shelf until needed.
In fact, a number of waterborne outbreaks have been specifically
linked to improper or unsanitary home water storage methods.
Why store water?
In many parts of the world, storage of drinking water is a routine
occurrence, especially in homes lacking a connected source for potable
water. Even in developed regions, the desire to store water for
further treatment comes either from a lack of trust in municipal
water supplies or the need for preparedness of a natural disaster
or any other event that might compromise one's water supply. Regardless
of the reason, drinking water collected from unsafe sources outside
the home and held in household storage vessels are susceptible to
contamination either at the source or during storage.
Several factors complicate
the storage of water (see Table 1) and may compromise the
quality of the water collected. Even if stored water supplies are
properly collected in sterile containers and treated to remove any
original populations of viruses and bacteria, the presence of disinfectant-resistant
protozoan pathogens may still pose a problem. Filtration combined
with disinfection or boiling for three minutes remains the most
effective way to remove these hearty organisms.
Table 1. Potential routes
of stored water contaminants
- Contamination via hands
- Contaminated collection
vessels (re-used containers)
- Bacterial regrowth (pathogen
- Potential presences of
organisms resistant to disinfectants (Cryptosporidium)
Evidence of contamination
Studies of water storage practices in underdeveloped countries provide
the best epidemiological evidence linking stored water to infectious
disease transmission. Awareness of potential contamination sources
and knowledge of the safeguards available can help maintain safe
water storage practices in any region.
A 1979 evaluation
of metropolitan Lagos, Nigeria3, indicated
an 11.2 percent prevalence rate of Entamoeba histolytica,
a pathogenic protozoa. Interestingly, the commonality was not associated
with type of water supply but by storage of household supplies.
Likewise, a study of an agricultural-based community in Zimbabwe4 showed that household stored
water had a higher percentage of samples contaminated with E.
coli than tap water used to fill the storage vessels.
Following a cholera
epidemic with more than 533,000 documented cases and 4,700 deaths
that began in Peru in January 1991, researchers found that contaminated
water stored in the home was one of the greatest risk factors for
the disease.5 Evaluation of stored water supplies
showed progressive contamination during distribution and storage,
where fecal coliform counts were highest in water from household
storage containers and lowest in city well water.
A study highlighted
in a 1995 article in the Journal of the American Medical Association
(JAMA) described a two-component prevention strategy, which
allows an individual to disinfect drinking water immediately after
collection (point-of-use disinfection) and then to store the water
in narrow-mouthed, closed vessels designed to prevent recontamination
(safe storage).2 The
study determined combination of new disinfectant generators and
better storage vessel designs make home water storage a practical
and inexpensive alternative. It further stated that a home treatment
and storage approach empowers households and communities that lack
potable water to protect themselves against a variety of waterborne
pathogens. That, in turn, has the potential to decrease the incidence
of waterborne diarrheal disease.
Although there are potential hazards related to storing water in
the home, there are a number of recommended procedures to follow
if the need arises (see Table 2). Maintaining good hygiene
during storage into sterile collection vessels is probably the most
effective means of reducing the chance of microbial infections.
Narrow-mouthed vessels-less than 10 centimeters-are useful to discourage
dipping utensils or hands into the water. If the water was non-potable
initially, it may be chemically treated (i.e., chlorine or iodine)
or boiled prior to bottling or drinking. Keep in mind, though, that
routine chemical treatments may cause adverse health effects over
time (i.e., cancer effects).
Table 2. Maximizing stored
- Use new or sterilized
containers made of food-grade plastic
- Wash hands prior to collection
of water and avoid touching the mouth or inner lid of the
- Carefully fill the vessel
with water from the highest quality source available
- Boil or chemically treat
(disinfect) potentially contaminated drinking water
- Store containers in the
coolest, darkest space possible
- Consume or replace supplies
about every six (6) months, or less
Food grade storage
containers made of high-density polyethylene, i.e., common plastic
milk containers, should be used to prevent leaching of toxic materials
such as lead or vinyl chloride from ceramic and PVC containers,
respectively. Storing filled containers in a cool, dark place will
reduce growth of harmful microbes but not completely eliminate their
proliferation. It's best to consume or replace stored water supplies
frequently (about every 6 months).
As preparation for
an emergency, it's advisable to store supplies for treating water,
such as equipment for boiling or chlorine or iodine tablets (see
Table 3). Crude methods of filtration by using common household
supplies such as newspaper, filter paper, gauze and cotton cloth
may also help reduce pathogen transmission. Research shows that
this method, along with chlorine treatment can produce an emergency
potable water source from snow or rain.1
3. Procedures for emergency drinking water disinfection
- BoilingVigorous boiling for
three minutes will kill any waterborne pathogen
label of common household bleach for instructions or add
10 drops of a one-percent bleach solution per quart of clear
water. Double amount if water is cloudy. Mix and wait 30
household iodine (2 percent U.S.P.) may be added using 5
drops per quart of clear water or 10 drops per quart for
cloudy water. Mix and wait at least 30 minutes.*
chlorine and iodine tablets are available also at drug, camping
and sporting goods stores.
Using the highest level of purified water possible as the source
for stored supplies is vital in maximizing the long-term quality
of stored water. Municipal tap water is frequently monitored in
the United States and is required to meet a certain level of standards
set by the U.S. Environmental Protection Agency. Point-of-use treatment
devices provide an additional means for quality control of untreated
water supplies and further improvement of municipal water sources.
When these treatment
benefits aren't available, an awareness of potential sources of
contamination and knowledge of safeguards available enables safe
maintenance of water storage in the home or any other situation.
1. Kozlicic, A., et al., "Improvised purification methods for
obtaining individual drinking water supply under war and extreme
shortage conditions," Prehospital Disaster Medicine,
2. Mintz, E.D., et al., "Safe water treatment and storage in
the home: A practical new strategy to prevent waterborne disease,"
JAMA, 273:948-53, 1995.
3. Oyerinde, J.P., et al., "The epidemiology of Entamoeba histolytica
in a Nigerian urban population," International Journal of
Epidemiology, 8:55-9, 1979.
4. Simango, C., et al., "Bacterial contamination of food and
household stored drinking water in a farmworker community in Zimbabwe,"
Central African Journal of Medicine, 38:143-9, 1992.
5. Swerdlow, D.L., et al., "Waterborne transmission of epidemic
cholera in Trujillo, Peru: lessons for a continent at risk,"
Lancet, 340:28-33, 1992.