: MEDIA / PRESS RELEASES / MAKING SURE WATER FILTER IS CLEAN : :

The Star/ Wednesday 26 May 2004

If you visit any shopping centers in Klang Valley nowadays, you are bound to find a stall or shop selling water filters or water purifier. In the last 5 years water filters has become a necessity for most Klang Valley households. Almost every other house has some kind of water filtration system installed at either the point-of-use (kitchen tap) or at the point-of-entry (after water meter to filter water supply for the whole house). The purpose of installing water filters is obvious enough-everyone wants clean water, but with the plethora of filters available in the market, how does one choose a filter that actually works? Can the filter you purchased 3 years ago produce the same water quality as when you first purchased it?

Promises and warranties for water filters are given fairly liberally by most sellers. Most filters work well in their first 6 months. What happens after that? The only way to know if your filter is still working fine and the water that you drink is safe is to do frequent testing of your filtered water.

This article will attempt to give readers some understanding of the common water quality parameters that is measured to determine the health of our drinking water. In addition, a brief recommendation on the type of water filtration system for treating a particular problem will also be given.

Water is frequently described as "the universal solvent". Because of its ability to dissolve most elements, it picks up or dissolves small amount of numerous elements such as metals, rocks & minerals, gases, dust, rust and other inorganic and organic substances/chemicals with which it comes in contact. In addition, water is an excellent environment for countless micro-organisms, some of which can be harmful to man.

Turbidity
Murky water, rust color water, muddy water, water with silt and sediments, these are common complaints of a physical property of water measured by its turbidity.

Turbidity in water is caused by very small particles that remain suspended and tend to float in the water. The standard measurement for turbidity is reported in Nephelometric Turbidity Unit (NTU) and this is measured using a turbidity meter (an analyzing equipment based on light beam). According to the Ministry of Health (MOH) & World Health Organization's Drinking Water Quality Standards, the maximum acceptable value for turbidity in drinking water is 5NTU. A good point-of use filter should deliver drinking water of less than 0.5 NTU, while a good point-of entry filter should achieve filtered water of less than 5 NTU.

pH
pH indicates the alkalinity or acidity of a given water. pH strength is measured on a scale that goes from 0 to 14. 7, the midpoint, is the measure of neutral water, neither acid nor alkaline. pH more than 7 indicate alkaline solution, while pH less than 7 indicate acidic solution. pH can be easily measured by using a pH meter. pH of between 6.5-9.0 is recommended by the Ministry of Health (MOH) Drinking Water Quality Standards. Most of the time Malaysian municipal water falls under these ranges, as such there is no need to alter the pH of our water. Reverse osmosis water may become slightly more acidic as carbon dioxide dissolve in it, while water produce by an ionizer/alkaline water machine can be either acidic or alkaline.

Color
Color in water can be due to a number of reasons. First of all, a high turbidity in water can contribute to a sense of a certain color in the water due to the suspended particles like silt and rust. Color can be independent from turbidity, for example chrysanthemum tea can be turbidity free but yellow in color. Color in our municipal water is commonly due to turbidity, color pigments release by decaying plants as well as industrial dye. Color measurement is usually expressed in True Color Unit(TCU) or Hazen unit, and this is measured using a spectro-photometer. According to the Ministry of Health (MOH) & World Health Organization's Drinking Water Quality Standards, the maximum acceptable value for color in drinking water is 15TCU. Color in water can be treated easily with filters that employ activated carbon as a filtration media, while industrial dye may require more advance system like ozone or bleaching system to remove the color.

Hardness
Whitish scale deposits in pipes, lime deposit in wash basins & cooking pans, soap curd that doesn't lather are common problems encountered when you have "hard" water at home. Hardness is a common quality of water which contains dissolved compounds of calcium and magnesium. Hardness is usually expressed in parts-per-million (ppm) as calcium carbonate equivalent. Hardness can be measured using various methods, for example hardness strip test, spectro-photometer, hand-held hardness meter etc. According to the Ministry of Health (MOH) & World Health Organization's Drinking Water Quality Standards, the maximum acceptable value for hardness in drinking water is 500ppm. Most Malaysian municipal water hardness falls between 20 to 150ppm. Apart from causing the above mentioned problems, calcium and magnesium minerals are actually non-harmful when consumed; they may even be beneficial to the human body. Water filtered by an R.O system, or Deionization system will be low in hardness while a calcium ionizer can concentrate calcium ion and produce water with a higher hardness value.

Coliform Bacteria
These are organisms of the bacteria family, the most well known member of this group of bacteria is Escherichia Coli (E. Coli). These bacteria exists and grows as part of the normal micro-organism population in the digestive tract of warm blooded animals, thus it serves as a strong indicator of sewage contamination of our water. Detecting its presence in a water supply can be easily done using a Presence/Absence coliform test kit, or growing them in culture media in the lab.

According to the Ministry of Health (MOH) & World Health Organization's Drinking Water Quality Standards, coliform bacteria should be absent in any 100mls of sample taken. Coliform bacteria can be easily filtered using a ceramic filter with pore size that is less than 0.5 micron. It can also be remove or destroy using an R.O system or Ultraviolet water disinfection system, however these system needs to be regularly serviced and maintained to ensure they are really free of bacteria.

Total Dissolved Solids (TDS)
This is a water quality parameter that measures the total weight of the solids that are dissolved in the water. These solids can be from mineral source, chemicals, inorganic and organic substances etc. TDS is measured in parts-per-million (ppm) using a TDS meter or weighing the weight of the residue of an evaporated water sample. According to the Ministry of Health (MOH) & World Health Organization's Drinking Water Quality Standards, the maximum acceptable value for TDS is 1000ppm. Most Malaysian municipal water TDS falls between 30 to 180ppm. TDS in water can be reduce by using the distillation process, R.O system and to a certain extend a deionization system and ozone system. These are relatively expansive systems that require substantial maintenance and servicing. In a residential system, the disadvantages outweighs the benefits.

Other Parameters

Chlorine
Chlorine and its degradation by-products are frequently measured to determine its level in our municipal water to ensure adequate disinfection as well as to ensure they exist in acceptable level that will not affect human health. Chlorine can be filtered at the point-of-use or at the point-of-entry by system that employs activated carbon as a filtration media.

Iron and Manganese
Iron residue causes a brownish staining of laundry while manganese residue causes black speckle on laundry. These mineral are present in higher amount if water is sourced from underground.

Nitrate and Ammonia
The presence of these compounds in excessive quantity in the water usually signifies improper septic or waste disposal or industrial contamination.

Heavy Metals
These are metals with high molecular weight that are present in small amount in the water. Lead may come from old piping that is made from lead, presence of mercury signify industrial contamination, while arsenic can be due to industrial contamination or poisoning.

The parameters above are all measured in parts-per-million (ppm) using a spectro-photometer.