Questions and Answers
On Point-Of-Use And Point-Of-Entry Units
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D C 20460
Questions and Answers
On Point-Of-Use And Point-Of-Entry Units
1) Q. What is the difference betveen a point-of-use/point-of-
entry unit and a home water treatment system?
A. The terms point-of-use and point-of-entry unit are used
to describe any type of water treatment unit which is
either adding or removing substances from the water.
Point-of-use (POU) devices are units which deliver
treated water to a drinking water faucet only. Point-
of-entry (POE) devices are units which are installed at
the entry point to the home and treat all the water
entering the home. For the purposes of this factsheet
the terms POU/POE or home water treatment unit will be
used to describe any type of device designed for the
treatment of water.
2) Q. How do POU/POE devices differ?
A. There are several primary areas where POU/POE units
differ:
1) Treatment Technologies: Different technologies
are designed to remove or treat different
contaminants. Therefore, the type of contamination
problem should be clearly identified before
purchasing any unit.
2) Treatment Capabilities! The degree to which a
unit will remove contaminants will depend upon a
number of factors including the characteristics of
the contaminant, contact time with the water, and
concentration of contaminants in the water. Most
units, such as activated carbon, are available in
several forms and the treatment capabilities may
vary from one to the other.
-1-
-------
2) A. Cont’d
3) Point of Application : POU/POE units are designed for
application at either the point-of-use (POU) or at the
entry point to the house (POE). POTJ units will treat
only the water flowing from one point and POE devices
will treat all the water flowing throughout the house.
POU units may be designed to fit either on the counter
or below the sink.
3) Q. Is there a difference between a purifier and a filter?
A. A purifier makes microbiologically contaminated
water or water of unknown source or quality
microbiologically safe for human consumption.
This is not easily achievable using POU/POE
treatment and very few units are considered water
purifiers. Actually, according to the “Guide
Standard and Protocol For Testing Microbiological
Purifiers” (a guidance document used by EPAtS
Office of Pesticides and Toxic Substances in the
registration of filtration units) an official
definition would be one that refers to the
microbiological safety of the water. A
microbiological water purifier is a unit which
“must remove, kill or inactivate all types of
disease-causing microorganisms from the water”.
To qualify, a microbiological purifier must treat
or remove organisms to the following standards:
99.9999% reduction in bacteria, 99.99% reduction
in viruses, and 99.9% reduction in cysts. Most
filters are not recognized by the Office of
Pesticides and Toxic Substances as being able to
remove disease causing microbes from the water and
are only used to enhance the qualities of
municipal water. Hence, filters should only be
used on water that is microbio]ogically safe.
—2-
-------
4) Q. What is the difference between an EPA establishment
number and an EPA registration number?
A. In POU/POE units an EPA registration number (EPA Reg.
NO.) indicates that the filtration unit contains a
pesticide (Such as silver) and is regulated under the
Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA). It is also evidence that the registrant had
the unit tested to insure that the pesticide does not
leach from the unit into the treated water at excess
concentrations. For example, when silver is used in
filtration units the registrant must show that the unit
was tested and does not leach silver in excess of
5Oppb. It is important to understand that registration
is not an approval or endorsement of the product by
EPA.
An EPA establishment number (EPA Est. NO.) identifies a
manufacturing plant where pesticides or pesticide
products are produced or manufactured. It is possible
for a manufacturer to have both an EPA establishment
and registration number. If both a “Reg.” and an
“Est.” number appear on the product, then a chemical is
present. If only an “Est.” number appear on the
product, then only a plant is identified. Filter units
which contain chemicals and make pesticidal claims
(such as being bacteriostatic) that do not have and
“EPA Est. NO.” on the unit’s label mean a unit is
probably being illegally sold and should be reported to
the appropriate EPA regional Office of Pesticides and
Toxic Substances. Complaints can be directly reported
to the Office of Compliance Monitoring, Tip and
Complaint, EN-342, 401 N Street, SW, Washington, DC
20460, (202) 382—7835.
5) Q. What is meant by “bacteriostatic”?
A. Bacteriostatic means that an agent is being employed
which may inhibit (slow down) the growth of bacteria
within the POU/POE unit for a period of time. It does
not mean that pre-existing bacteria in the water are
being removed or killed or that bacterial counts in the
treated water will be influenced in any way. For
example, carbon can be impregnated with silver to
inhibit the growth of bacteria within the filter unit.
—3—
-------
6) Q. Does EPA recommend the use of POU/POE devices?
A. If water is received from a public water system and
that system is meeting all of the requirements of the
National Primary Drinking Water Regulations (NPDWRs),
then EPA believes that water is safe to drink, and from
a health standpoint, no additional water treatment is
necessary. However, even though water may be meeting
the requirements, it is possible that it may contain
certain undesirable qualities such as unpleasant tastes
or odors. With proper maintenance, some POU,/POE units
can help consumers manage taste and odor problems of
municipal water and reduce contamination in Public
Water Systems (PWS) to below EPA and State standards.
EPA does not recommend the use of POE/POU filter units
on private well water. They are only recommended for
use on municipally treated water.
EPA will allow a public water system to use a POE
device to meet Maximum Contaminant Levels (MCLs) only
if the system meets specific conditions.
7) Q. How does an activated carbon filter work? What will it
remove?
A. Activated carbon systems are available in several
forms: Granular activated carbon (GAC), powdered
activated carbon (PAC), and pressed carbon block
filters. Activated carbon is a material capable of
adsorbing gases, liquids, and/or dissolved contaminants
on its surface. The carbon is full of pores which trap
contaminants when water passes through the filter.The
ultimate effectiveness of activated carbon is dependent
upon an even flow throughout the carbon (as opposed to
passing directly through a limited number of channels),
and a flow rate of the water sufficiently low enough to
ensure adequate contact time. Host activated carbon
systems use a carbon cartridge which is replaced as
needed. Other activated carbon systems come self-
contained and are discarded after a specific amount of
time or a specified quantity of water passes through
the system.
Activated carbon can remove many organic chemical
contaminants (such as pesticides and herbicides) and
chlorine, given enough contact time. Activated
carbon filters can also remove color, taste, and odor
problems. Most have not been found to be effective in
the removal of microbes and dissolved minerals, salts
and metals, including lead. Thus, carbon filters by
themselves should not be used on water which is
microbiologically unsafe.
—4—
-------
8) Q. How does reverse osmosis work and what viii it remove?
A. A basic Reverse Osmosis (RO) system consists of a
reverse osmosis module, a storage tank, and a separate
tank; however, many RO systems also include an
activated carbon component. The module, which is the
heart of the system, uses pressure to force water
through a semi-permeable membrane. The membrane pores
are so small (0.0005 micron) that they block almost all
foreign particles in the water, but allow water to pass
through and collect in the storage tank. Chemicals and
particles which do not pass through the membrane, and
about 75% of the water entering the system, viii be
discarded. Hence, 4 gallons of water will yield
approximately 1 gallon of filtered water. Treated
water will come out slower than at a regular tap so a
storage tank is necessary to ensure that an adequate
supply of treated water is available when needed.
Reverse osmosis is effective at removing most
inorganics. It will substantially reduce all suspended
and dissolved matter from the water including bacteria
and cysts, dissolved minerals, organic substances with
large molecules or higher molecular weights and
trihaloinethanes (disinfection by-products). Some RO
units are subject to bacterial degradation and are not
recommended for use on microbiologically unsafe water.
9) Q. Some POU/POE units are impregnated with silver. What
does this mean and does It make the unit more
effective?
A. In some POU/POE systems silver is used as a
bacteriostatic agent, meaning that it is put into
POU/POE units as an agent to inhibit (slow down) the
growth of bacteria within the unit for a period of
time. Studies conducted by EPA’S Office of Research
and Development (ORD) have shown limited water quality
effects from silver impregnation. A long-term Canadian
study of one silver impregnated carbon filter, showed
that there was initial inhibition of bacterial growth.
However, the carbon filter eventually produced growth
of bacteria. Presently, water quality effects appear to
be negligible.
—5—
-------
10) Q. What are the health effects of drinking water which
contain excessive levels of silver?
A. EPA examined the available data on silver and concluded
that the only adverse effect from exposure is Argyria
(a bluish-metallic discoloration of the skin). When
silver accumulates in body tissue the effects are
permanent. However, when silver accumulates in the
blood stream, effects have been shown to disappear with
time. EPA considers Argyria a cosmetic effect since it
does not impair the functioning of the body or present
other physiological problems. EPA believes that the
newly proposed secondary (90 ppb) limit for silver in
drinking water will prevent Argyria. Furthermore, the
occurrence of Argyria in the U.S. is extremely rare and
almost always due to the ingestion of pharmaceutical or
other high-silver content substances.
11) Q. EPA’S Office Of Drinking Water (ODW) has recently
proposed to drop the current 5oppb Maximum Contaminant
Level (MCL) for silver. At the same time a new
secondary, non-enforceable standard of 9Oppb was
proposed (54 E 22062). Does this mean that POU/POE
units impregnated with silver will no longer be
required to have an EPA registration?
A. Under the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA), POU/POE units which are
impregnated with any type of pesticide (including
silver), are required to be registered. Whether the
removal of the existing standard for silver will effect
this program is not known at this time. The situation
is currently under evaluation.
12) Q. Which brands of POU/POE devices work best?
A. EPA does not test individual brands of
POU/POE devices. However, there are certain
technologies which are effective under
specific conditions. Given enough
information, EPA can suggest a type of
technology appropriate for a given
contamination problem. This factsheet,
developed by EPA, will provide the consumer
with the basic information needed when
purchasing a POU/POE unit.
—6—
-------
13) Q. Who regulates POU/POE manufacturers?
A. With the exception of having an “EPA Reg. NO.” and an
“EPA Est. NO.” under FIFRA, EPA has no federal
regulations or standards pertaining to POU/POE
manufacturers. However, the Food and Drug
Administration has regulations for medical devices.
Persons who feel that they have been the victim of
misleading sales practices or false product claims
should contact their state water supply office. Some
states have developed regulations pertaining to product
claims and sales practices. Individuals should also
consult with local consumer groups and the better
business bureau for information and to verify if any
other complaints have been made. For consumers who
wish to file a complaint alleging misleading sales
practices or false product claims, contact the Federal
Trade Commission at FTC, 6th and Pennsylvania Avenue,
NW, Washington, DC 20580 or call (202) 326—2000.
14) Q. Is EPA considering any regulations which would require
homes to install POU/POE units?
A. No. EPA has never considered any such regulations.
For consumers served by a community water system,
POU/POE units are suggested only as a possible means of
enhancing water quality.
15) Q. If I don’t use my POTJ/POE device for a while, will
bacteria grow in it?
A. Yes. Bacteria can collect and multiply in the filter
unit during periods of non-use, especially in warm
climates. However, there is no known health
consequence as a result of this. POU/POE owners should
follow the manufacturers recommendations for proper
care of the unit after periods of non-use.
—7—
-------
16) Q. How long wi]]. POUJPOE systems be effective against
contaminants, when should the filter be changed?
A. POU/POE systems effectiveness will, vary depending on
the degree of contamination, amount of water processed,
and type of technology being used. In order to ensure
your safety, the maintenance instructions specified by
the manufacturer should be followed carefully.
17) Q. Where can I get more information about POU/POE systems?
A. The following two organizations can be contacted for
more information about POU/POE systems.
1) The Water Quality Association (WQA) is a private,
not—for—profit international trade association
representing firms and individuals engaged in a].].
aspects of the water supply industry. Membership
is voluntary so not all POU/POE manufacturers may
be represented. WQA can be contacted by calling
(708) 505-0160. Written requests for information
can be directed to the Water Quality Association,
P.O. Box 606, Lisle, Illinois, 60532.
2) The National Sanitation Foundation (NSF) is an
independent, not-for-profit organization of
scientists, engineers, technicians, educators, and
analysts. NSF evaluates and tests products,
systems, and services against NSF standards, other
voluntary consensus standards, and government
regulations. NSF can be contacted by calling
(313) 769—8010. Written requests for information
can be directed to The National Sanitation
Foundation, 3475 Plymouth Road, Ann Arbor,
Michigan, 48105.
While both WQA and NSF operate voluntary certification
programs, neither organization rates or recommends
specific brands of POU/POE systems.
A General information factsheet on POU/POE devices is
also available from the Federal Trade Commission,
Office of Consumer/Business Education, 6th and
Pennsylvania, NW, Washington, D.C., 20580. By phone:
(202) 326—3650.
-8—
-------
18) Q. How many different POU/POE Lanufacturers operate in the
United States?
A. According to the Water Quality Association, there are
approximately 400 POU/POE manufacturers in the United
States.
—9—
------- |