"You don't miss your water until your well runs dry"
Y2K Preparedness for Possible Water Supply Disruptions
by Ingrid Schulze

(This paper is distributed courtesy of NOVA Y2K and Ingrid Shulze.
It may be copied and distributed freely as long as it is printed in its entirety and no fee is charged)

Y2K and Our Water Supply

In the United States, we often take clean water for granted, and
open the tap with little or no regard for the preciousness of this
resource. Hurricanes, earthquakes, floods and ice storms can all
disrupt public water supplies. Water supplies are also vulnerable
to disruptions stemming from the Year 2000 computer problem.

The Y2K problem has the potential to affect drinking water supplies
internally at the water treatment plant through failures of
computers, software or embedded computer systems that control pumps,
filtration systems, treatment and disinfection processes, and
aerators. Water facilities are also vulnerable to failures of
personal computers and software packages, customer billing and
materials tracking systems, and a host of embedded systems other
than those that directly control water treatment and supply (for
example, internal telecommunications equipment, building HVAC and
security systems, automated sampling and analytical equipment).Each
drinking water supplier has a unique mix of computer systems on
which it is dependent. Approximately 30% of all programmable logic
controllers with date functions at water and wastewater facilities
have some type of Y2K compliance issue.facilities are also
vulnerable to failures of personal computers and software packages,
customer billing and materials tracking systems, and a host of
embedded systems other than those that directly control water
treatment and supply (for example, internal telecommunications
equipment, building HVAC and security systems, automated sampling
and analytical equipment).Each drinking water supplier has a unique
mix of computer systems on which it is dependent. Approximately 30%
of all programmable logic controllers with date functions at water
and wastewater facilities have some type of Y2K compliance issue...
are also vulnerable to failures of personal computers and software
packages, customer billing and materials tracking systems, and a
host of embedded systems other than those that directly control
water treatment and supply (for example, internal telecommunications
equipment, building HVAC and security systems, automated sampling
and analytical equipment).
(See the Association of Metropolitan Water Agencies (AMWA) website
http//www.amwa-water.org/y2k/action_plan.html. The AMWA website
also has a full list of equipment, instruments and systems that must
be checked for embedded chip problems at water treatment plants..)

Indirectly (external to the water treatment facility), drinking
water quantity and quality also depend on:(external to the water
treatment facility), drinking water quantity and quality also depend
on(external to the water treatment facility), drinking water
quantity and quality also depend on

--Electricity generated by fossil fuel (oil, gas and coal) and/or
nuclear power plants;

--Adequate supply and timely delivery of treatment and
disinfecting chemicals from chemical manufacturers and
suppliers;

--Telecommunications support from phone companies and
equipment manufacturers that permit the operation of
supply chains of electricity, treatment chemicals and
interactions with customers;

--Maintaining protection of the sources of water. (For
example, the quality of surface water such as streams and
rivers could be degraded by Y2K-related failures of
upstream municipal and industrial wastewater treatment
facilities.)

The most comprehensive source of information about the Y2K readiness of water utilities is a voluntary survey conducted jointly in
July/August of 1998 by AMWA, the American Water Works Association
(AWWA) and the National Association of Water Companies (NAWC).
Out of 3700 utilities (which together serve a total of 204 million
people) that received a survey, 725 responded, a response rate of
about 20% . Statistically, a voluntary survey with a response rate
of 20% cannot be used to draw conclusions about the population of
3700 systems. If the nonresponding utilities are less prepared than
those that did respond, then the survey results are misleading.
According to AWWA, however, response rates for the two largest
categories of water utilities were 100%. Survey questions related
primarily to the status of internal Y2K planning, implementation and
testing; external planning, implementation and testing (i.e., Y2K
compliance status of external service providers and vendors); and
contingency planning status of the water utilities.

In terms of internal Y2K readiness of the responding utilities,
81% were confident at the time of the survey that they would
complete their internal Y2K planning, implementation and testing in
time for the year 2000. The percentages were higher for large and
very large systems, 89% and 100%, respectively, than for smaller
water systems.

Utilities were less confident that all their external Y2K planning,
implementation and testing would be complete before the year 2000
begins. Thus, only 67% of large and 90% of very large utilities
were confident that they would not be affected by "power outages,
communications failures including data transmission, or a shortage
of water treatment chemicals if their external service providers and
vendors have Year 2000 problems". The overall percentage was 65%.

Finally, at the time of the AMWA survey (July/August 1998), only 27%
of responding water utilities had Y2K-specific contingency plans.
Since last summer, this proportion has probably gone up, however.
Contingency plans would include such things as making sure the
utility can operate systems manually, filling water storage tanks to
capacity, and stockpiling fuel and treatment chemicals in the event
of supply chain disruptions.

Why Should You Prepare for Potential Water Supply Disruptions?

While the apparent internal readiness of large, and especially, very
large utilities is encouraging, the AMWA survey results should not
be a reason for complacency. Given the low response rate of the
survey, and the fact that it was a voluntary survey involving
self-reported data, it is impossible to assess how biased the survey
results are. The survey also does not give much detail about how
far advanced water utilities are in their Y2K remediation plans. It
is clear, however, that even large and very large water utilities
were concerned about their external dependencies on suppliers,
transportation, electric utilities and telecommunications. Thirty
percent of large and !0% of very large utilities were not confident
that this aspect of their Y2K preparations would be complete by
January 2000. Furthermore, even if water utilities are internally
and externally completely prepared for Y2K, they are still
vulnerable to failures of upstream municipal and industrial
wastewater treatment facilities. At the time this is being written
(2/1999), there is little public information available about the Y2K
readiness of wastewater treatment facilities.

Clean water is cheap in times of plenty, but it can be priceless in
times of need. Given the uncertainties in the existing data about
water utility Y2K readiness, the complex interdependencies of water
utilities with their suppliers and other infrastructure providers,
as well as the potentially serious risks of water supply
disruptions--water shortages, contamination of water supplies by
microorganisms or chemicals (e.g., due to pollution from upstream
facilities), waterborne disease outbreaks, etc.-- personal
contingency planning for clean drinking water is a common sense
precaution for individuals and families to take. Such personal
preparedness can be viewed as a form of health insurance.

How Can You Prepare for the Possibility of Water Supply Disruptions?

Preparing for possible water supply disruptions should involve at
least two things: some level of water storage as well as a means of
treating water of questionable quality. In addition, depending on
your assessment of the potential severity of water supply problems
in your area, a third component might be of interest, namely water
collection. Each of these subjects will be discussed below.

Water Storage

The most reliable way of insuring a minimum supply of clean water
for times of emergency is to store some. The following
recommendations for a water storage program are adapted from the
book, Making the Best of Basics: Family Preparedness Handbook:

1. Store water from the source that you are currently drinking from,
so that household members do not need to become accustomed to
different-tasting water.

2. Water should be stored in new, heavy duty, food-grade plastic
containers that have been thoroughly cleaned and have tight-fitting
lids. Food-grade containers are made of materials that meet Food
and Drug Administration standards for food storage. Ideally, your
water storage containers should also be sturdy enought to meet
Department of Transportation standards for strength and
transportability (i.e., shipping grade containers). These come in
various sizes from 5 to 55 gallons. Five gallon containers are
generally designed for stacking and weigh about 40 pounds filled
with water, which is about the maximum that most people can readily
carry. Fifty-five gallon food grade plastic barrels with a siphon
pump are also available for storing larger quantities of water.
Containers should be cleaned thoroughly with anti-bacterial soap and
then be permitted to air-dry.

3. Do NOT reuse lightweight plastic containers previously filled
with food or, especially, with chemicals. Remnants of previous
contents, even though they may not be readily detectable by smell or
color, may result in a contaminated water supply.

4. Store water away from paint, petroleum based products, acids or
anything that smells bad such as equipment, animal waste,
fertilizer, etc. Plastic containers "breathe", so they can become
contaminated by substances with strong odors, especially petroleum
based products.

5. Never use metal containers for water storage. Some have a
coating on the inside that can give stored water an unpleasant
taste, and some will rust.

6. Rotate your water supply in order to insure its quality and
shelf life. In theory, bacteria- free water that is stored in
clean, tightly closed containers away from sunlight will stay safe
for several years. However, unless you plan to sterilize water and
containers at the time of storage,

is always better to rotate stored water supplies every 6 months, if
at all possible. If stored water has not been rotated regularly,
then treatment prior to use (with bleach, for example) can be used
to insure that water is drinkable (see below).

While Stevens does not recommend the use of lightweight food
containers for water storage, clear plastic drink containers
previously used for soft drinks, fruit juices and bottled water (the
ones that say #1 and PETE in the recycling symbol on the bottom) can
be reused for water storage if they are cleaned thoroughly before
use. Since these bottles were not specifically designed for
longterm water storage, however, it is probably prudent not to
store them outdoors or at freezing or very high temperatures,
particularly once they have been filled with water. They should
also be stored out of the sun. Note that translucent (#2 HDPE)
plastic milk jugs should NOT be used for water storage since they
are biodegradable, plus milk residues may contaminate water stored
in them.

One of the simplest, cheapest things you can do NOW to start a water
storage program is to start cleaning out and saving clear plastic
(#1, PETE) soda bottles each time you finish one, instead of
recycling them or throwing them away.

For people who wish to store larger quantities of water outdoors, it
can be stored in large outdoor tanks or cisterns. These come in
several different materials ( e.g., linear polyethylene) and many
different sizes and can be purchased from a number of suppliers. Be sure the tank you purchase is approved for
drinking water storage. To be used as an emergency water supply,
water tanks can be filled with tapwater from an outdoor faucet while
water is plentiful, and later used as drinking water with minimal
treatment (see "Disinfecting water with bleach" under Water
Treatment). In an emergency, such a cistern could also be refilled
with rainwater from gutter downspouts. However, it should be
emphasized that roof runoff is not clean, and must be extensively
purified before using it as drinking water, since it can contain
microorganisms as well as toxic leachates from roof shingles (see
section on "Water Sources" below).

How Much Water to Store?

Perhaps the surest way to have enough drinking water for your family
in case of supply disruptions is to store it. The following
discussion assumes a two week supply of stored water per person.
Two weeks, it should be emphasized, is an arbitrary length of time.
It is NOT based on an assessment of the length of possible water
supply disruptions due to the Year 2000 problem. Rather, it is
based on the maximum amount of space most people might reasonably devote to water storage, and on the assumption that water supply disruptions (whatever the cause) might involve intermittent
shortages or contamination, and that some minimum amounts of clean water would be available, if at higher prices. A two week supply of
stored water would also permit a household to help unprepared
neighbors in the event of shorter duration water supply problems.

Stevens distinguishes between subsistence and maintenance level
water storage requirements. The minimum approach recommended for insuring that a household has at least a subsistence-level water
supply for water emergencies is to store one gallon per day per
person for a two week period. Thus, assuming a four- person family,
this comes out to:

1 gallon x 14 days x 4 people = 56 gallons.

The subsistence level provides barely enough water for each family
member for drinking, brushing teeth, and washing hands with a
washcloth, but it is not enough water for food preparation. Note
that drinking at least 2 quarts/person per day is recommended; and
high levels of physical activity, hot weather, illness, and nursing
a baby are all likely to increase water needs over and above two
quarts/day.

A slightly more generous level of water storage than the
subsistence level is two gallons per day per person for a two week
period, which is equal to:

2 gallons x 14 days x 4 people = 112 gallons,

or approximately the contents of two 55 gallon drums. Stevens calls
this a maintenance level of water storage. This permits some water
use for cooking and food preparation, cleaning utensils and
equipment, and for washing the body with a washcloth. It should be
noted that both subsistence and maintenance levels of water storage
provide only a fraction of the amount of water most Americans use in
a day.

This paper will not discuss what to do about wastewater disposal
(flushing the toilet, etc.) in the event of public water supply
disruptions. This subject is covered in NOVA Y2K's waste disposal
paper.

Water Sources

In the event of unexpected water supply disruptions, whatever the
cause, a number of indoor and outdoor emergency water sources can
be utilized (see Appendix 1). Note that water from some of these
sources cannot be considered drinkable without prior treatment!
Water treatment will be discussed in the following section.

If clean interior water sources such as the plumbing system are
exhausted, two obvious emergency water sources are rainwater and
snow. However, unless rainwater or snow are captured directly as
they fall from the sky in clean containers, they cannot be used
without prior treatment.

In some places, for example, Texas, rainwater harvesting for
household use is being practiced by increasing numbers of people,
and is actually encouraged by the state government. With an
appropriate water collection surface (usually a house roof made of
an appropriate material such as metal or slate), a water storage
system, and access to a modest source of electricity, a household
can satisfy all its water needs through rainwater collection, as
long as average annual rainfall exceeds 30 inches per year. The
Texas Guide to Rainwater Harvesting and Banks and Heinichen discuss
the theory and practice of rainwater collection for household use in
some detail, and the former publication also provides a number of
Texas case studies. Such relatively elaborate rainwater collection
systems may be more than most people are willing or able to install
purely as an emergency water source for possible water supply
disruptions, however.

What most people in single family homes or even townhouses can
afford to install is one or two rainbarrels under their gutter
downspouts. Rainbarrels can be had through gardening catalogs
(e.g., Gardener's Supply Catalog) or local suppliers. In a pinch,
even a brand new garbage can can be used as a rainbarrel.

It is important to emphasize here that while rainwater as it comes
out of the sky may be clean (apart from the presence of airborne
pollutants), water that comes off a roof is not clean enough for
drinking and cooking! It can contain a whole range of potential
contaminants from trees, birds, insects, etc. Furthermore, many
roofs these days are made of composite asphalt shingles or other
materials that can leach toxic substances into the rainwater as it
runs over the roof surface. Thus, water that comes off a house roof
MUST be treated before use! However, while this water should not be
used for drinking water purposes without extensive treatment (e.g.,
distillation or a series of filters, depending on the contaminants
of concern), it may be useable as is in an emergency situation for
washing or rinsing things other than food or drink containers, for
instance, bathing, washing clothes, flushing the toilet, etc.

Finally, in an emergency situation, rainwater can be collected
directly in clean containers with a large surface area (i.e.,
without first running off a dirty collection surface such as a
roof), in clean backyard kiddie pools, for example, and it will
require only minimal or no treatment before use as drinking water,
depending on the cleanliness of the container in which it is
collected.

Water Treatment

Water storage is probably the best way to ensure that you have a
source of clean water in the event of any kind of water supply
disruptions, including possible Y2K related ones. However, water is
heavy (8 lb/ gallon) and takes up a great deal of space. Thus,
because water is so essential to life, a well-prepared household
should also have at least one or more means of treating water to
make it drinkable. Having the ability to treat potentially
contaminated water also allows people to help neighbors who may not
be prepared.

Water contaminants can be one of three general types: particles such
as debris and sediment, chemical contaminants, or biological
contaminants. Elimination of debris or sediment from water is
usually done with some kind of large-pored filter. Debris can be
removed by simply filtering water through several layers of densely
woven cloth. For smaller particles, various kinds of sediment
filters are available, which will be discussed further below.

Water that is contaminated with microorganisms or toxic chemicals
need not look, smell or taste bad! Elimination of biological
contaminants from water is referred to as "disinfection" of the
water. Chemical contaminants CANNOT be removed by disinfection but can be eliminated by a variety of filters or by distillation. Water
can be disinfected through the use of heat (boiling) or light
(ultraviolet light), by chemical methods such as chlorine or iodine,
or by filtration or distillation of the water. Table 2 summarizes
the uses and effectiveness of various water treatment methods.
(Table 2 and much of the section on water treatment are based on The
Drinking Water Book, by Colin Ingram.)

Simple water disinfection without equipment

The boiling method.One of the simplest ways of treating contaminated
water or water of questionable quality in order to make it drinkable
in an emergency is to boil it at a rolling boil for at least 10
minutes. Note that debris should be filtered or strained out of
the water before it is boiled (some light but densely woven cloth
will do for this purpose). Obviously,

disinfection of water by boiling requires a heat source and fuel.
Boiled water can be made to taste less "flat" by pouring it back
and forth between two containers a number of times (aeration), by
letting it stand for a few hours, or by adding a pinch of salt to
each quart of water. Note that while boiling can kill
microorganisms present in water and remove some volatile chemicals,
it does not remove nonvolatile chemicals (i.e., most kinds of
chemicals) or toxic metals (for example, those that might be present
in runoff from roofs with composite shingles).

Water disinfection with chlorine Water can also be disinfected using
chlorine in the form of household bleach, granular calcium
hypochlorite, or chlorine tablets.

Water Treatment

Household bleach such as Clorox, which usually contains 5.25% sodium hypochlorite, can be used to treat reasonably large quantities of
water relatively cheaply. The bleach used should be plain bleach
with no soap additives, phosphates or perfumes. Stevens gives the
following instructions for treating water with bleach:

Disinfecting water with bleach:

1) If water is clear, add 8 drops of bleach per gallon of water, or
* teaspon per 5 gallons.
If water is cloudy, add 16 drops bleach per gallon, or 1
teaspoon per 5 gallons.

(Do not add too much bleach.)

2) Thoroughly mix bleach in water by stirring briskly.

3) Let water stand for at least 30 minutes. The mixture should have
a distinct bleach (chlorine) smell or taste after the waiting
period. If no chlorine smell is detected, add the same dose of
bleach to the water and let mixture stand an additional 15-20
minutes. Note that the colder and dirtier the water is, the longer
is the time needed for the chlorine to kill microorganisms. If the
chlorine taste of the treated water is unpleasant, the water can be
poured from one clean container to another several times, or be
allowed to stand exposed to air for a few hours.

Disinfection with calcium hypochlorite Another way of treating
contaminated water with chlorine is to use high-test granular
calcium hypochlorite, which is sold, among other places, in swimming
pool supply stores as HTH (for "high-test hypochlorite"). This
calcium hypochlorite has between 65-75% of its weight as available
chlorine. One virtue of buying granular hypochlorite rather than
Clorox for water disinfection is that more disinfecting power can be
stored as a solid in a smaller volume.

In order to use granular calcium hypochlorite for emergency water
disinfection, you must first make what is called a "stock solution"
by dissolving one heaping teaspoon (about 1/4 ounce) of high-test
granular calcium hypochlorite per two gallons of water. This "stock
solution" is NOT drinkable! In order to disinfect questionable
water, add one part of your stock solution to each 100 parts of
water to be treated. This is approximately equivalent to adding 1
pint of stock chlorine solution to each 12.5 gallons of water to be
disinfected. To remove excessive chlorine odor after disinfection,
water can be aerated by pouring from one container to another.

Chlorine tablets Chlorine tablets for disinfection of drinking
water can also be purchased from some drug or sporting goods stores
and should be used as stated on the package. When no instructions
are available, use one tablet to disinfect each quart of water to be
treated.

Water disinfection with iodine Iodine tablets for drinking water
disinfection can also be purchased at some drug or sporting goods
stores, and should be used according to instructions. If no
instructions are available, one tablet should be used for each quart
of water to be treated.

Tincture of iodine (a 2% solution of iodine) from a first aid kit
can also be used to disinfect water. To use for water disinfection,
20 drops of USP tincture of iodine should be added per gallon of
clear water; or 40 drops per gallon of cloudy water.

Water disinfection with iodine has several drawbacks, however.
Some people cannot tolerate the odor or taste of iodine- treated
water. People with thyroid problems should not drink iodine treated
water because of possible effects on their thyroid condition, nor
should it be used by pregnant or nursing women. Also, iodine may
not be effective against organisms such as Giardia or
Cryptosporidium, and should thus not be used for disinfecting water
from surface water sources (lakes, rivers or springs).

Water filters and other water treatment units

Water that is of questionable quality can also be treated using
various kinds of water filters and other treatment/purification
devices. There is currently a bewildering array of such devices on
the market in a wide range of prices. In this section, I will make
a brief attempt to demystify this technology. Most of the following
discussion is based on The Drinking Water Book by Ingram.

The four main types of water treatment or purification units are
filters, distillers, reverse osmosis units (which can be viewed as a
type of filter), and purifiers that use ultraviolet (UV) light.
Except for some camping and travel type filters, most of these
units are designed for stationary use at one location, that is, they
are not readily portable. Also, distillers and UV purifiers
require electricity.

Characteristics of water filters.

Water filters can be divided into several basic types: sediment
filters, carbon filters, filters for microorganisms, mineral/metal
filters, and reverse osmosis units. These basic filter types can
either be purchased separately, or in some cases, as part of a
single unit. Some water filters are incorporated in portable units
intended for water treatment when camping, travelling or for
emergency use in a disaster situation, or they can be part of a
larger stationary home water purification system.

Sediment filters are often used as the first stage in a drinking
water purification system to keep the following stages from becoming
clogged up. They are not designed to be used alone. They filter
out dirt and other particles and are rated according to the smallest
particle sizes they can trap. For example, a 5 micron filter will
trap particles that are 5 microns in diameter or larger. With a
dirty water source, two sediment filters may be used in conjunction,
a coarser (50-100 microns) filter first, and then a finer (5 micron)
one. Pleated-film type sediment filters tend to last longer before
they are clogged up and are more resistant to bacterial growth than
the wound-string or rigid foam type sediment filters.

Activated carbon filters can be either granular or block carbon
filters. They are used to remove a wide variety of chemical
pollutants from water, but they CANNOT remove microorganisms or
dissolved minerals. Carbon filters are especially useful for
organic chemicals such as pesticides, herbicides and industrial
chemicals. They can also remove radon, chlorine, and unpleasant
tastes or smells. Carbon block filters are more effective than
granular carbon filters, because channels often develop in the
granular type where water can flow through without contacting the
carbon. However, the dense pores of carbon block filters can easily
become clogged unless they are preceded by a sediment filter. Also,
as mentioned above, carbon filters cannot disinfect water (that is,
they do not remove microorganisms); in fact, they may provide a
breeding ground for organisms. For all these reasons, carbon
filters should be replaced at regular intervals. Many of the most
commonly sold household water filters are some kind of activated
carbon filter. One of their most common uses is for removing
chlorine from municipal water supplies.

Filters for microorganisms. Three classes of waterborne
microorganisms that need to be eliminated from water in order to
make it drinkable include bacteria, parasites and viruses. Filters
used to remove parasites and bacteria from water include ceramic and
membrane (reverse osmosis) filters. Ceramic filters with a pore
size of about 0.2 microns are used extensively by disaster relief
agencies such as the International Red Cross and by armies of many
countries. These ceramic filters are sturdy (as long as they are
not dropped on a hard surface) and portable, and can be used
indefinitely since they can be cleaned by scrubbing them
periodically. Viruses, because they are so small (<0.1 micron),
cannot be removed with most filters, with two exceptions discussed
below.

Two filters that are at least partially effective in removing or
inactivating viruses in water are ceramic/silver filters
(British Berkefeld and MSR), and iodine-resin filters. The iodine-resin filter uses a microfilter to
trap cysts and parasites, and iodine that is tightly bonded to a
resin filter medium kills waterborne bacteria and viruses.
According to Ingram, iodine resin filters are thought to be more
effective against viruses than ceramic-silver filters. However,
ceramic-silver filters can be used indefinitely, while iodine-resin
filters must be replaced periodically.

Membrane filters are used in reverse osmosis (RO) water purifiers.
Reverse osmosis purifies water by letting it pass through a thin
membrane with very tiny pores or holes (MSR WATERWORKS II). Larger pollutant molecules
are left behind because they cannot get through the pores. The
advantage of RO is that it removes a wide variety of pollutants
from toxic minerals and organic pollutants to some microorganisms.
However, because the pores of the reverse osmosis membrane are not
uniform in size, this method can only partially remove
microorganisms from water, and should not, by itself, be used for
disinfection of water. Some other disadvantages of reverse osmosis
units includes the fact that they tend to waste water and that the
filtering process is very slow. Also, use of RO in a low pressure
water system may require use of a booster pump to force the water
through the RO membrane. Finally, the RO membrane is rather
delicate and can fail prematurely after a few months if there are
bacteria or high levels of dissolved solids in the water to be
treated.

One other type of filter that should be mentioned here is the
mineral/metal filter. These include two kinds: alumina and redox
filters. They can remove dissolved metals such as lead (as opposed
to metals that are in the form of particles). Alumina filters
attract and trap dissolved metals, but do not remove chlorine,
organic chemicals or microorganisms. Redox filters (short for
reduction/oxidation) exchange toxic metals in water for zinc and
copper. Redox filters can also partially reduce levels of bacteria
in water and trap chlorine. The performance of an alumina filter
deteriorates with time faster than that of a redox filter.

Home water purification systems

The filters discussed above include both portable and stationary
types. Some, such as ceramic-silver and iodine resin filters, can
be made eminently portable and are often used for camping, travel or
emergency use (British Berkefeld and MSR). Some, e.g., sediment filters, are used almost
exclusively in combination with other types of filters or water
treatment devices. Home water purification systems often involve a
combination of two or more types of filters or other water
purification devices. They range from water pitcher, countertop and
undersink styles to whole house systems. Ingram reviews and
analyzes the effectiveness and costs of some of the best home water
purification systems. These range from various kind of filters to
reverse osmosis, distillation, and ultraviolet type purifiers.
Ingram explains which combinations of treatment approaches are most
effective against which kinds of water contaminants, including
microorganisms, minerals, organic chemicals, radon, additives such
as chlorine, and undesired tastes and smells, and he discusses the
pros and cons of specific models and combinations of units.

Two remaining types of water purification devices, distillers and
ultraviolet (UV) type water purifiers, that are used in home
treatment systems have yet to be discussed. Both require
electricity, so use in a power outage is not possible unless you
have an alternate power source. Distillers work by turning water
into steam and then recondensing it, so that impurities that do not
evaporate are left behind. The virtue of distillers is that they
can produce high quality water very reliably, and they can remove
all types of pollutants except some volatile organic chemicals
(which evaporate when the water evaporates). A disadvantage of
distillers is that they require a good deal of electric power to
heat and evaporate the water. Also, water cooled distillers waste
water (4-5 gallons per gallon of purified water made). Air cooled
distillers waste less water but are not as energy-efficient as water
cooled distillers.

Ultraviolet purifiers disinfect water using a special ultraviolet
lamp. Thus, they require electricity, but not as much as
distillers. UV purifiers only disinfect water, and they cannot
remove chemicals from water. Thus, UV purifiers must be used in
combination with filters if chemical water contaminants are a
concern. Also, UV purifiers require sediment prefilters, since
solids or particles in water can shield microorganisms from the UV
light. If cysts such as those of Giardia are a concern (which have
hard coverings that UV light cannot penetrate), a carbon block
filter must also be used, and if toxic minerals are present, a redox
filter must be used as well.

What are the best water treatment methods to have in case of
possible Y2K disruptions?

Unless you can be certain your water utility will have no problems
whatsoever due to the Y2K problem, it is prudent to combine some
level of water storage, as discussed above, with one or more water
treatment options. The level of precautions any particular
individual or family takes is likely to depend on a number of
factors, including state of health of family members, knowledge or
assumptions about theY2K status of local infrastructure, financial
circumstances, degree of risk aversion, and other considerations,
e.g., environmental concerns.

The cheapest and easiest means of disinfecting water (i.e., killing
microorganisms in water) is to buy a couple of extra bottles of
Clorox at the grocery store. At 8-16 drops per gallon of water to
be disinfected, a gallon bottle of Clorox will disinfect over 7000
gallons of clear water (and half that much cloudy water). As
discussed in the NOVA Y2K waste disposal paper, Clorox can also be
used to disinfect human wastes when flushing toilets is
impossible. Other relatively inexpensive chemical disinfection
options are calcium hypochlorite or some form of iodine. It should
be noted, however, that at least two organisms, Giardia and
cryptosporidium, may not be entirely eliminated by chlorine or
iodine treatment, and iodine should not be used by some people. If a
heat source and fuel are available, then boiling water at a rolling
boil for 10 minutes is an excellent means of disinfection that can
also kill Giardia and cryptosporidium.

Portable water filters sold for camping, travel and disaster
preparedness provide another relatively inexpensive means of
disinfecting water (many cost less than $150). Filters have the
virtue of not requiring a heat source like boiling water does; they
do not introduce chemicals into the water; and they can be taken
along whereever you go. Also, ceramic filters also have a very long
working life.

Testing Water Quality

Discussion of water quality testing is beyond the scope of this
paper. However, Ingram has a good discussion of water testing in
The Drinking Water Book.. He points out that water quality testing
can be exceedingly expensive, but that some reputable test labs
offer comprehensive automated testing for reasonable prices (which
can still run several hundred dollars for a complete battery of
tests). Two labs that Ingram mentions are Spectrum Labs and
National Testing Laboratories. It is also possible to get a list
of certified water testing labs from EPA's Safe Drinking Water
website or hotline.

Conclusions

Based on studies of hurricane and earthquake preparedness, some
proportion of people in a community will not undertake any kind of
personal contingency planning for Y2K, either because they are
unwilling or unable to do so. In order to help those who cannot or
will not prepare themselves, local governments can undertake some
relatively simple and inexpensive actions before the end of 1999 to
help insure some protection from water supply interruptions or
contamination for all its citizens. These might include such things
as filling public swimming pools with water, purchasing some large
water tanks and a store of disinfectants such as calcium
hypochlorite, and requiring citizens to save containers that can be
used for water storage which would otherwise be recycled (such as
PETE soda bottles).

A community water utility that is well prepared for possible Y2K
problems will have developed a variety of contingency plans for
different internal and external failure scenarios. However, few
communities have the ability to store large amounts of finished
drinking water. Most large drinking water systems have 2-5 days
storage capacity. Because clean water is so critical to human
health, personal preparedness for possible water supply disruptions
is an important form of insurance. Being prepared also makes you
part of the solution, rather than part of the problem. Every
person who is prepared is one fewer individual that is dependent on
emergency response organizations, if water supplies are disrupted by
Y2K problems or any other emergency.

Endnotes

Above-ground outdoor water storage tanks can only be used in colder
regions of the country in winter if they are insulated, for example
with fiberglass or polyurethane; otherwise they can crack if the
water inside freezes.

Note that rainwater collection has important environmental benefits,
since it can help people conserve water and helps retard stormwater
runoff (which can cause downstream flooding and damage to streams
and rivers.) While people in the eastern U.S. often think of water
scarcity as a Southwestern problem, high population growth in
metropolitan areas like Washington, DC, is causing planners to start
thinking about means of reducing water demand (Drinking Water Supply
in the Washington, DC Metropolitan Area: Prospects and Options for
the 21st Century, League of Women Voters, February 1999).

It is important to distinguish between water treatment that makes
water quality acceptable for short-term use in an emergency, and
water purification that makes water suitable for long-term use.

Removal of debris and use of a sediment prefilter is desirable with
all water treatment methods. It is particularly essential for a
carbon block filter, reverse osmosis, and UV disinfection. Carbon
block filters and reverse osmosis membranes are easily clogged, and
water turbidity (cloudiness) reduces the effectiveness of UV
disinfection.

Carbon block filters (even though their rated pore size is smaller
than most bacteria) cannot be used to remove bacteria and parasites
from water because the carbon pore size is not uniform enough and
the seals around the filters permit some leakage.

According to Katadyn Products, Inc., ceramic filters have some
ability to remove viruses because many viruses in water are attached
to bacteria, so that by filtering out bacteria, viruses are
partially removed also.

Copyright © Ingrid Shulze