Water Purification System

TDS in Water

Since the beginning of time, water has been both praised and blamed for good health and human
ills. We now know the real functions of water in the human body are to serve as a solvent and medium
for the transport of nutrients and wastes to and from cells throughout the body, a regulator of
temperature, a lubricator of joints and other tissues, and a participant in our body’s biochemical
reactions. It is the H2O in water and not the dissolved and suspended minerals and other constituents
that carry out these functions. Total dissolved solids (TDS) is a measure of the combined content of all
inorganic and organic matter which is found in solution in water. Water low in TDS is defined in this
paper as that containing between 1-100 milligrams per liter (mg/l) of TDS. This is typical of the water
quality obtained from distillation, reverse osmosis, and deionization point-of-use water treatment of
public or private water supplies that are generally available to consumers in the world. Worldwide, there
are no agencies having scientific data to support that drinking water with low TDS will have adverse
health effects. There is a recommendation regarding high TDS, which is to drink water with less than
500mg/L. Some people speculate that drinking highly purified water, treated by distillation, reverse
osmosis, or deionization, “leaches” minerals from the body and thus causes mineral deficiencies with
subsequent ill health effects.
An isolated report, a summary of Russian studies available through the World Health Organization,
has recommended that fluid and electrolytes are better replaced with water containing a minimum of
100 mg/L of TDS. However, this may pertain more to situations in the human body during heavy
exertion and sweating. This situation does not have anything to do with low TDS or demineralized water
for normal drinking and cooking purposes. Even in warm weather exercise, the greatest danger is that
of dehydration, and the proper advice to ward it off is to drink lots of plain water. It is the market for
sports drinks which are formulated to help replace the sugar compounds, glucose in the blood and
glycogen in the muscles that are burned in prolonged exercise. Sports drinks are formulated to help
replace the sugar compounds – glucose in the blood, glycogen in the muscles – and electrolytes – salt,
calcium, and potassium that keep cells in proper electrolytic balance – that may be burned and depleted
after an hour or more of hard exercise.
The scope of this paper is limited to answering whether low TDS water contributes to the loss of
minerals from body tissues, producing associated harmful side effects. The types of minerals -e.g.,
calcium versus sodium, or hard water versus soft water– and the toxicity of minerals -e.g., lead,
cadmium, brackish, or saline waters- are not an issue in this report. Information on the body’s
homeostasis mechanisms, community water supplies with natural TDS less than 50 mg/L, historic use
of distilled water with less than 3 mg/L TDS on board Navy ships, the US Environmental Protection
Agency’s (USEPA) response to this issue, and other evidence are presented to demonstrate that the
consumption of water with low levels of minerals is safe.
The Natural Control of Mineral Concentration in the Human Body
A better understanding of the effect of low TDS water on the human body requires a basic
understanding of the body’s mechanism in this respect. Following is a description of the relevant
mechanism (Guyton 2006):
“Homeostasis is the maintenance of static or constant conditions in the internal body
environment. This natural process controls the mineral (ion) and the water concentrations in the
body fluids within narrow limits inside and outside all the cells in all the organs and tissues of the
body. The kidneys are most important in maintaining constant ion concentrations (including
sodium, potassium, calcium, etc.) through elimination and reabsorption. In homeostasis, three
body fluids are involved: plasma (approximately 3/5 of the blood volume); interstitial fluid (the
fluid between cells); and intracellular (fluid inside the cells). The concentration of sodium ions is
highest outside the cell and that of potassium ions is highest inside the cell. When the osmotic
pressure is high on one side of the cell membrane (high concentration of ions) and low on the
other side, water moves across the cell membrane from the dilute side toward the other side to
equalize the osmotic pressure. This phenomenon is known as osmosis. This is unlike reverse
osmosis which occurs when outside pressure is applied to the concentrated side, pushing the
water back to the dilute side. The normal osmolality (concentration of ions) of all these fluids is
about 300 milliosmoles per liter (mOsm/L), or 9,000 mg/L.
Any changes from normal in ion concentration across the cell membrane is corrected in one
minute or less because water moves quickly through cell membranes. Thus, small changes in
osmolality from drinking purified water (0-100 mg/L TDS) are quickly brought to equilibrium.
The kidneys control the overall concentration of the constituents of body fluids. It filters about
180 liters (165 quarts) of water per day, but over 99% is reabsorbed and only 1.0-1.5 liters are
eliminated as urine. If the osmolality of the fluid to be filtered by the kidney is lower than normal
(low solute concentration – such as low TDS water) nervous and hormonal feedback
mechanisms cause the kidney to excrete more water than normal and thus maintain the ion
concentration in the body fluid to normal values. The opposite is true if the ion concentration of
the fluid to be filtered is higher than normal. This kidney homeostatic mechanism keeps the
body fluid osmolality normal. The osmolality of the fluid to be filtered by the kidney is controlled
to ± 3% to maintain it at the normal level of 300 mOsm/L. The three basic hormonal and
nervous control systems triggered by abnormal ion concentration in the body fluids to be filtered
by the kidney are antidiuretic hormone (ADH) from the pituitary gland, aldosterone from the
adrenal glands, and thirst (as osmolality rise of about 1% causes thirst).
Because of these kidney control mechanisms, drinking one liter of water would cause the urine
output to increase about nine times after about 45 minutes (due to absorption of water in the
gut) and continue for about two hours. Thus, the concentrations of solutes in the blood and
other body fluids are quickly maintained by the kidney through homeostasis. These control
mechanisms keep the sodium concentration at ± 7%. Calcium secretion is controlled by
parathyroid hormone to ± a few percent in the extracellular body fluid. Also, saliva increases the
ion concentrations during water intake. The concentration of sodium chloride in saliva is typically
15 milliequivalents per liter (mEq/L) or 877 mg/L; that of potassium ion is about 30 mEq/L (1170
mg/L). As low TDS water is consumed, it is combined with saliva which increases the TDS
before it reaches the gut to be absorbed, (e.g., each one mL of saliva can increase the TDS
level in eight ounces of water consumed by about 10 mg/L).
Therefore, it is evident that consumption by a healthy person of low TDS water alone cannot
cause unhealthy systems. ‘Healthy person’ means free of disease, hormonal problems, etc., and
not necessarily a healthy diet. Homeostasis is maintained by diet as are other body functions. If
homeostasis is not maintained because of major diet deficiencies, disease, or hormonal
dysfunction, consuming low TDS water would be a minor (if any) factor in any observed
symptoms. It is apparent that disease, physiological dysfunction, or major nutritional deficiencies
may cause a “leaching” problem, but not consuming one to two liters of low TDS water on a
daily basis.”
Literature Search and Review
A review of the literature has shown that there is very little information published in western scientific
literature that relates the consumption of low TDS water to physiological effects on the human body. A
report submitted to the World Health Organization in 1980 contained an annex reviewing work that had
been reported in Russian literature. Current literature searches do not uncover any official translation of
any of the articles cited in that annex. The annex concludes that consumption of water with less than
100 mg/L disturbs the body’s water/salt balance, promoting the release of sodium, potassium, chloride,
and calcium ions from the body of animals or humans, imposing a stress on the mechanism of
homeostasis, promoting changes in the gastrointestinal muscles and mucosa, and reducing the thirst
quenching capacity of the water. This annex has been intensively reviewed by many scientific experts,
including Dr. Lee Rozelle and Dr. Ronald L. Wathen (see Appendix A for the complete reviews).
US EPA’s Dr. Edward V. Ohanian, Chief of Human Risk Assessment Branch wrote, “Drinking water
supplies a number of minerals that are important to human health. However, drinking water is normally
a minor source of these minerals. Typically, the diet is the major source of these beneficial minerals. I
am not aware of any data adequate to support the conclusion that water with low levels of minerals is
An additional search performed in 2014 reviewed a WHO publication on Nutrients in Drinking Water,
which includes the meeting notes and related articles discussed in a 2003 meeting.2,5,9
There are chapters in this paper discussing consumption of demineralized water, which suggest that more
research may be necessary to determine if guidelines should be established for minimum drinking
water TDS limits, but the overall symposium conclusions are silent on the matter. The most recent
WHO Guidelines for Drinking Water Quality (4th edition, 2011) discusses palatability and scaling issues
at high TDS, but does not discuss low TDS. It also states that no health-based guideline value for TDS
has been proposed.

Discussion of Field Experiences
There are no known scientific data which clearly demonstrate that the consumption of low TDS
water by humans will or will not lead to harmful effects on the human body. However, a number of field
experiences can be cited which support the premise that the consumption of such water by humans
does not cause such harmful effects. There are no known documented experiences which show that
consuming low TDS water will create any long-term health effects.
The US Navy has used distilled sea water for human consumption for approximately 40 years.3 TDS
levels below 3 mg/L have been reported and consumption of this water for months at a time is common
on submarines. No health problems have been reported by the Navy. The US Army uses reverse
osmosis units to provide drinking water for soldiers in the field. The USEPA conducted a project in San
Ysidro, New Mexico in which the TDS was dropped from 800 mg/L to a range of 40 to 70 mg/L. No
health effects were observed. NASA has reported no ill effects from the consumption of approximately
0.05 mg/L TDS water on board space craft.
Possibly the largest field study of human consumption of low TDS water is within the United States
where municipal systems are delivering water in this category. Millions of people currently consume
such water, and this practice has gone on for decades. Exact data are difficult to obtain due to seasonal
changes, use of blended water from multiple sources, and changes of sources. In addition, thousands
of private wells, as well as numerous small municipal systems in the US produce low TDS water. No
known health effects or problems have been reported as a result of this widespread practice.
Thousands of TDS reduction devices have been sold residentially in the United States for decades. No
reports of mineral depletion or health effects are known as a result of the consumption of this water. In
a field test in Boulder, Colorado with about 50 families, an experimental, zero discharge water system
provided drinking water containing about. 0.05 ppm TDS. No ill health effects were caused as a result
of drinking this water. In conclusion, the field experiences cited suggest that there are no long-term ill
health effects, specifically the mineral leaching from human tissue, due to the consumption of low TDS
It has been concluded that the consumption of low TDS water, naturally occurring or received from a
treatment process, does not result in harmful effects to the human body. This is based upon the
following points:
• No public health organization with authority over the drinking water quality anywhere in the
world has enacted or even proposed a minimum requirement for total dissolved minerals in
drinking water.
• The human body’s own control mechanism (homeostasis) regulates the mineral content of the
body fluids and the discharge of different types of ions from the body of normal health
individuals drinking water with low or high mineral content.
• Several types of scientific literature searches have found no harmful effects to the human body
attributable to the consumption of low TDS water.
• Review of the Soviet report has shown that the scientific methods used are questionable and
the conclusions are either vague or unsupported by the data.
• Many examples of real-world situations in which large populations have been and continue to be
provided exclusively with low TDS water without any reported unusual or ill health effects,
establishes the safety of consuming such waters by human beings.



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