Safe to drink
Safe to drink
By : PRASANNA RAMAN (Source: NST 2008/06/02)
Though our tap water may look clear, it does not mean that it is clean. |
What Kryptonite is to Superman is what ultraviolet light is to viruses, bacteria and protozoans in our drinking water, reports PRASANNA RAMAN.
| Various pollutants make their way into our taps, says Professor Chan Ngai Weng. |
“Although your tap water may look clear, it does not necessarily mean that it’s clean. because the water has to be channelled to homes, exposing it to various pollutants that make their way into the water while on its way to our taps,” said Professor Chan Ngai Weng of Universiti Sains Malaysia.
Four main criteria,
“Treated water from treatment plants cannot be guaranteed safe for drinking unless the water is taken straight from the source. This is he added, determine the quality of our tap water. They are raw water quality, quality of water treatment, quality of main pipes, and the quality of our home pipes and tanks.Although the best source of water should ideally come from the mountains, the fact is, said Chan, who is also president of Water Watch Penang, 97 per cent of our water supply comes from our rivers.
Chan listed organic, chemical, solid and squatter wastes as the biggest river pollutants.
Organic sources include domestic and industrial wastes, industrial-agro and livestock effluents, while chemical sources include heavy metals, nitrates and toxic chemicals from agriculture and chemical industries.
The solid waste include sediments from construction, agriculture, and housing development while squatter sources include excreta, greywater, garbage, old furniture and other household materials.
“In the Klang Valley, 80 tonnes of solid wastes are dumped into the Klang river every day,” said Chan.
“So if your home is situated miles away from the water treatment plant and it needs to travel past agricultural or even industrial areas, contaminants and pollutants can make their way into the pipes via leaks and water theft.
In addition, the quality of main pipes is also pertinent.
“Old and rusty steel and iron pipes will add on more pollutants like rust and sediments into the water that’s coming to our homes,” he said, adding that even if all the main pipes are replaced with new ones, the old pipes and tanks in our homes can do the necessary harm.
How then does one ensure safe and clean water? Treat it with Ultraviolet (UV) light, said Chan.
What Kryptonite is to Superman is what UV light is to viruses, bacteria and protozoans in our tap water.
“It’s one of the most effective disinfectant methods while preserving the natural minerals in the water which boiling just removes,” said Chan.
Although UV disinfectant makes people wonder how “light” can kill bacteria, Chan said, it has been proven to do so effectively for many years.
UV technology has been around for more than 70 years, and its effectiveness for both water and air pollution has been well documented both scientifically and commercially.
UV germicidal irradiation has been used to destroy the microbes that cause indoor air and water pollution. It is used widely in the medical industry to sanitise rooms and equipment.
“Copied from nature’s disinfectant and purification method, the UV treatment is a means of killing or rendering harmless microorganisms in our tap water. These microorganisms can range from bacteria and viruses to algae and protozoa,” he said.
Citing an example, Chan said, cryptosporidium is a protozoan that is often associated with diarrhoea in humans. Although that protozoa strain can resist many common disinfectants, including chlorine, it is nevertheless sensitive to UV light, as the light kills it.
“Tap water treated with UV means no removal of beneficial minerals, no change in taste, odour, pH or conductivity nor the general chemistry of the water. Coupled with a good filter, it will remove the turbidity and sediments that’s in our tap water,” he said.
Common microorganisms destroyed by UV light:
z Bacillus anthracis
z Corynebacterium diphtheriae
z Dysentary bacilli (diarrhoea)
z Escherichia coli (diarrhoea)
z Legionella pneumophilia
z Mycobacterium tuberculosis
z Pseudomonas aeruginosa
z Salmonella (food poisoning)
z Salmonella paratyphi (enteric fever)
z Salmonella typhosa (typhoid fever)
z Shigella dysentariae (dysentery)
z Shigella flexneri (dysentery)
z Staphylococcus epidermidis
z Streptococcus faecaelis
z Vibro commo (cholera)
z Bacteriophage (E. Coli)
z Hepatitis
z Influenza
z Poliovirus (poliomyelitis)
z Baker’s yeast