Environment & Ecology
Fluoride Problem in Drinking
Fluoride occurs naturally in most water supplies and may be added in larger
concentrations above the natural background in order to promote dental health. High
levels of fluoride are known to cause health problems. Fluoride concentrations in
municipal water supplies were measured using an ion-selective electrode. Fluoride was
detected in 23 of the 25 samples collected, all sites reported a concentration well below
EPA’s standard of 4 ppm and the WHO’s standard of 1.5 ppm.
“...fluoride prevents dental caries
predominately after eruption of the
tooth into the mouth, and its actions
primarily are topical for both adults
CDC (1999). Achievements in Public Health, 1900-1999: Fluoridation of
Drinking Water to Prevent Dental Caries. MMWR, 48(41); 933-940, October 22.
Problem due to excess fluoride:
Dental fluorosis: Due to heavy intake of fluoride specially during the teeth
development stage may result into severe damage to the teeth's, can result into
disfigurement of teeth
Severe: mottling with enamel pitting and/or loss
Moderate: mottling but no enamel pitting or loss
Problem due to excess fluoride:
Skeletal fluorosis: is a bone disease caused by excessive consumption of fluoride. In
advanced cases, skeletal fluorosis causes pain and damage to bones and joints. The
fluoride begins to push away and replace the other nutrients that make up bone, such as
calcium.Skeletal Fluorosis is found to be most widespread in India and China, the two largest
countries. skeletal fluorosis is unfortunately affecting millions of people. The World
Health Organization, or WHO, has made recent estimates that about 2.7 million people
in China are affected by the crippling illness. In India, about half of its states (seventeen)
are considered endemic areas, or regions where a particular disease occurs often
Method of removal of fluoride from water.
1 . Distillation
Distillation is capable of removing just about anything (except volatile
compounds) from water. If you have a distiller, you can remove fluoride. The
obvious drawback to distillation is that the process is time and energy
consumptive and that it requires about 5 gallons of water to produce 1 gallon
of distilled water. Distillation also leaves the resulting water empty and
lifeless. If you use distilled water you need to add minerals (salts) back to the
2. Reverse Osmosis
Reverse osmosis (RO) represents a reverse of normal osmotic processes. It
relies on pressure and a semi-permeable membrane to remove contaminants
from water. RO can remove between 90 and 95% of fluoride (depending on the
efficiency of the system and depending on how well the system is maintained).
Contaminants are trapped by the RO membrane and flushed away in the waste
water. The process requires between 2 and 4 gallons of water to produce 1
gallon of RO water (depending on the quality of the water and the efficiency of
the RO unit). Source water with an abundance of contaminants (including hard
water) can reduce the efficiency of an RO system and it can shorten the life of
Similar to distillation, RO has a good track record for removing almost
everything from water.
3. Activated alumin
Fluoride is strongly attracted to activated alumina (corundum/aluminum
oxide) which has a large surface area with a huge array of tunnel-like
pores. For this reason, activated alumina is the most commonly used
fluoride removal media today. When used properly, it can remove up to
98% of the fluoride in water while also removing arsenic. The challenges
with activated alumina are many. First of all, since the process works by ion
exchange, the water must remain in contact with the media for an extended
period of time—long enough for the fluoride to be adsorbed by the media.
When the flow rate is faster than ¼ gallon/minute, there is not enough time
to adsorb all the fluoride in the water. Another difficulty with activated
alumina is that the media becomes saturated with fluoride. Depending on
the amount of media in the system (how large the filter is) and on the
amount of fluoride in the water, systems using activated alumina either
need to be recharged or replaced often. The last difficulty with activated
alumina is that aluminum is released into the treated water. This effectively
trades one problem for another. Some systems address this; others do not.
Bone-Char (BC) Carbon has been used for centuries to remove naturally-
occurring fluoride from water. It works similar to the way bones in the human
body attract fluoride. Bone contains a porous matrix that is rich in surface
ions. These can be readily replaced by fluoride and by some of the other
contaminants that arrive along with fluoride (heavy metals). Bone char
effectively removes a number of contaminants.
When used alone, BC-Carbon can remove up to 90% of the fluoride in water.
The efficiency of bone char can be improved by adding pre-filters that remove
heavy metals and other contaminants before exposure to the BC-carbon.
Bone char works best at a slightly acidic pH and may not work as well with