Gregthewaterman

Chlorine – A Cheap and Efficient Killer
Greg Reyneke CWSVI
The water that most of us drink is stored, treated and distributed to our homes by public
and private water utilities. Algae, bacteria, fungi and viruses can often be found in
untreated water. Americans have grown to expect a safe drinking water supply, but
achieving that level of safety is a complex task.
One hundred and fifty years ago, much of the USA’s water supply was teeming with various
forms of aquatic organisms. Waterborne diseases, such as cholera, typhoid, and dysentery,
were a serious health problem, and they are still major concerns in third?world nations
where over a billion people lack clean drinking water and almost two billion lack adequate
sewage systems. In 1992, the World Bank rated drinking water as first on its list of
preventable environmental hazards worldwide. Since 1991 the largest cholera epidemic in
recent history infected over 800,000 people from Peru to Mexico.
Waterborne microorganisms include coliforms and heterotrophic bacteria, viruses, and
protozoa. These organisms range in size from extremely small viruses to relatively large
cysts. They also vary greatly in the nature of their structure, lifecycle, and reproduction
characteristics. Pathogenic microorganisms occur naturally in lakes, streams, reservoirs,
and most surface water sources. Groundwater supplies are now becoming a subject of
increasing concern, because enteric viruses and other organisms can leach into the
groundwater system from the land application or burial of sewage sludge and other
treatment wastes.
Since water utilities first began using filtration and disinfection systems a century ago, the
risk of disease from drinking water in first?world countries has been greatly reduced.
Despite the significant progress that has been made, there are still numerous disease cases
resulting from contaminated drinking water in the United States. Health risks from aquatic
pathogens range from mild gastrointestinal distress to systemic disease and, in severe
cases, even death.
There are nearly 250,000 public water supply systems in the United States, serving
everything from the smallest towns to major metropolitan centers. Ninety percent of the
population receives its water through these community water systems, with the rest using
private wells or other individual sources. The United States Environmental Protection
Agency (EPA) ranks drinking water pollution as one of the top four environmental threats
to health. From 1971 to 1988, there were nearly 137,000 cases of waterborne disease??or
an average of 7,600 cases per year??reported in this country. It is suspected that there were
numerous undocumented cases as well, because many cases of gastrointestinal illness are
not recognized as part of a larger pattern of waterborne disease. It has been estimated that
only half of waterborne disease outbreaks in community water systems and about one
third of those in non?community systems are ever detected, investigated, or reported.
Microbes in tap water may be responsible for as much as one in three cases of
gastrointestinal illness in the United States. Rates of waterborne illness as high as 900,000
cases and 900 deaths per year have been estimated by the Natural Resources Defense
Council.
In the nineteenth century, progressive American communities began to separate the
drinking water delivered to users, from household and industrial wastes discharged into
sewage water systems. Many people in developing countries still do not have completely
separate drinking water and sewer systems. Water utilities in the USA began treating
drinking water with chlorine in 1908.
Chlorine and its compounds are currently used by over 98 percent of all U.S. water utilities
that disinfect drinking water; It is a cheap and efficient killer. By adding chlorine and its
compounds to drinking water, almost all organisms living in the water are killed. Chlorine
remains in the water as it is distributed to homes and businesses, thereby retaining much
of its ability to continue killing.
Although chlorine’s disinfectant value has been known for nearly a century, the
mechanism by which the compound kills or inactivates microorganisms is still not
completely understood.
The municipal water treatment process involves a series of different steps. Some of the
major steps include flocculation and coagulation (the joining of small particles of matter in
the water into larger ones that can more readily be removed), sedimentation (the settling
of suspended particles in the water to the bottom of basins from which they can be
removed), and filtration (the filtering or straining of the water through various types of
materials to remove much of the remaining suspended particles), as well as chemical
disinfection.
Chlorination is usually performed at several stages of the water treatment process. Pre
chlorination may be performed in the initial stages to combat algae and other aquatic life
that could interfere with treatment equipment and subsequent stages in the process. The
major chlorination stage, however, occurs as the final treatment step after the completion
of the other major cleaning processes, where the concentration and residual content of the
chlorine can be closely monitored. In this phase, the chemical is more active, and less
contact time is required to properly disinfect the water supply.
Chlorination can deactivate microorganisms by a variety of mechanisms, such as damage to
cell membranes, inhibition of specific enzymes, destruction of nucleic acids, and
mechanisms. The effectiveness of the chlorination process depends upon a variety of
factors, including chlorine concentration and contact time, water temperature, pH value,
and level of turbidity.
Chlorination is the cheapest, most effective way to disinfect water that is stored, processed
and distributed to homes and businesses at a municipal level. It is a cheap, efficient killer
that helps protect us all from deadly microbial diseases.
When chlorine is exposed to organic contaminants, certain disinfection byproducts (DBP’s)
are formed. For example, naturally occurring fulvic and humic acids in water will react with
chlorine to form a toxic soup containing numerous compounds such as trihalomethanes,
halocatic acids, trichloroacetic acid, and others. Chlorine will also react with the biofilm of
heterotrophic bacteria so common in piping systems and many water treatment devices.
Over 600 disinfection byproducts have been identified in drinking water treated by
chlorine or chloramine.
Epidemiological studies have related exposure to chlorine disinfection byproducts with
birth defects, pregnancy complications, certain cancers like bladder, rectal and kidney
(recent studies suggest there might even be a causal relationship between chlorine
byproducts and breast cancer), respiratory stress, eye irritation, skin damage, headaches
and fatigue.
Traditionally, the risk of chlorine and disinfection byproducts has been downplayed, since
the risk of non?chlorination is significantly greater. In fact the World Health Organization
(WHO) recently stated ? “the risk of death from pathogens is at least 100 to 1000 times
greater than the risk of cancer from disinfection byproducts
(DBPs) {and} the risk of
illness from pathogens is at least 10,000 to 1 million times greater than the risk of
cancer from DBPs” Essentially, the consumer is being told that they must choose between
illness and/or death from disease and microorganisms, or a steady decline in quality of life
from the permanent damage caused by chlorine and its byproducts of disinfection.
Thankfully, modern water improvement technology allows the consumer a third choice:?
Disinfect, and protect the water with industrial chemicals like chlorine until it
reaches the home, and then remove the chlorine and disinfection byproducts before
exposing ourselves to it through showering, bathing and drinking. This is analogous to
nature’s super?food ? the lowly banana…I learned the hard way as a youngster growing up
in Africa that the banana peel keeps its delicate fruit safe until ready to eat, and even
though the monkeys in our neighborhood ate banana peels, they were definitely not fit for
human consumption! I had to remove the protective skin before trying to eat the fruit.
As a water treatment professional, your primary responsibility is to provide your clients
with the very best water at a reasonable price in an environmentally responsible manner.
You have many options available to protect your client and their entire home from chlorine
and its dangerous disinfection byproducts. The simplest option is a replaceable carbon
cartridge, but it has a major downside – restricted flow and pressure. Most professionals
should rather consider a whole?house (POE) system that meets the consumers’ budget and
performance requirements. I always recommend the inclusion of bacteriostatic
components in carbon filters and encourage the use of an automatic disinfection injection
apparatus to ensure that the carbon absorption/adsorption media doesn’t become a haven
for bacteria.
Regardless of the system that you install for your client, always be sure to properly
disinfect it after installation with a non?chlorine disinfectant and replace the carbon and
other media on a regular maintenance schedule as recommended by the media and/or
equipment manufacturer.
Tastes
and
Odors
Chlorine DBP’s High
Flow
Rates
Bacteriostatic Self
Cleaning
Self
Disinfecting
GOOD
Carbon
Cartridge
BETTER
Upflow
Carbon Filter
Bacteriostatic
Upflow
Carbon Filter
Selfbackwashing
carbon filter
Bacteriostatic
Selfbackwashing
carbon filter
BEST
Bacteriostatic
selfbackwashing
carbon filter
with
automatic
disinfection
apparatus
Always be sure to use dechlorination equipment that is manufactured to comply with NSF
standards.
DEFINITIONS
Trihalomethanes – Chemical Compounds where three of the four hydrogen atoms of methane are
replaced by halogen atoms. Many trihalomethanes are used in industry and the home as solvents or
refrigerants. THM’s are generally considered environmental pollutants and many are actually
carcinogenic. The USEPA currently limits THM’s (chloroform, bromoform, bromodichloromethane,
and dibromochloromethane) to 80 ppb in treated water,
Haloacetic Acids – Carboxylic acids where a halogen atom replaces a hydrogen atom in acetic acid.
Haloacetic acids in varying forms are common disinfection byproducts of chlorination.
Chloroform – A trihalomethane reagent/solvent, considered an environmental hazard. Chlorofrm
is often inadvertently synthesized during the water treatment process when chlorine and related
compounds are added to water. The US Department of Health and Human Resources National
Toxicology Program’s eleventh report on carcinogens implicates chloroform as a human
carcinogen; a designation equivalent to International Agency for Research on Cancer class 2A. It has
been most readily associated with hepatocellular cancer. Chloroform once appeared as an
ingredient in toothpastes, cough syrups, ointments, and other pharmaceuticals, and was banned in
the USA as a consumer product ingredient in 1976.