A great number of cholera (haija) is reported in Nepal during each summer and monsoon. The people of Kathmandu, if they can afford it, usually buy bottled water for drinking purpose, without realizing that the quality of such water is often questionable. The outbreak of cholera incidents in households from seemingly “pure” bottled drinking water can be blamed on unregulated bottling plants which thrive on lax government regulation and supervision. Any call to increase the government scrutiny is useless to say the least given the current situation in the country. Although, the government supplied tap water, will likely fulfill the Nepal Standard for drinking water, what most people do not realize is that Nepal Water Supply Corporation (NWSC) has no control over its quality once it leaves their treatment plants, during transportation to end consumers. Any contaminations that take place while it travels to reach a Kathmandu home remain unbeknownst to the supplier as well as the consumer. Some, however, would recommend boiling or filtering the water received before consumption. Nepal Water Supply Corporation, after it has treated all the physical and chemical impurities in water, often adds enough chlorine to remove all biological contaminants, which still remains in some residual form “for the road.” Essentially, we can say that the purity the tap water you get might be dependent on how close your home is to the NWSC treatment plant.

Can you really trust the water that reaches your home through the government water supply system, a well, or a bottling company? This common conundrum has created a market space for home water filter systems which use surprisingly effective techniques to provide consumers with safe drinking water. These filters do not depend on one particular water purification technique but relies on multiple and treatments using different technologies. The water filters available in the market are in general affordable for an average family. Though the systems may be advertised as RO filtration system, it normally involves a series of different purification techniques occurring one after another. The common technologies used in this system include reverse osmosis, UV treatment, ultra filtration, ion exchange and activated charcoal.

  • Ultra filtration is filtration of water where water is passed through a very fine medium that traps particles in water. What differentiates ultra filtration from filtration is the size of the holes in the medium. The finer or smaller the holes are the better the water quality.

  • Reverse osmosis is also simple concept. Imagine in a container with water and salt solution separated by a semi permeable membrane that only allows movement of water molecules through it. Here, water from low salt concentration travels to high salt concentration area i.e. pure water will effortlessly move to higher salt solution due to osmotic pressure. In reverse osmosis, we put pressure on the salt solution for the water from it to move to the side with pure water through the membrane. In essence, reverse osmosis involves forcing water molecules through a semi-permeable membrane under pressure.

  • UV or ultraviolet rays are harmful to most living beings, especially bacteria. They can denature bacteria protein and DNA causing them to die. In the commonly found filters, water is passed through a UV chamber where UV rays remove such biological contaminants.

  • Ion exchange is responsible for removing heavy metals in water which are considered harmful. Metals like arsenic and mercury are trapped in the ion exchange chamber and are being replaced by harmless metal ions. An ion exchange system usually contains beads or a medium rich in sodium ion. When water passes through it, it traps metal ions and releases sodium in their stead. This process is also very effective for softening water.

  • Activated charcoal, which under medical setting is administered for most cases of poisoning, traps different harmful chemicals which may include pesticides and other pollutants through adsorption. Activated charcoal, which is also known as activated carbon, is derived from coal or coke. It is very porous in nature and provides a large surface area for chemical to get adsorbed into it that is, the harmful molecules adhere to the surface of activated charcoal.

A home filtration system usually utilizes these technologies to treat water into a form that is potable and harmless. This system requires electricity and wastes a lot of water. It is estimated that for each liter of water that is purified using reverse osmosis, four liters are wasted. The common alternative to filtration is chlorination of water. Usually a specific amount of chlorine is added in water which kills pathogens like bacteria and viruses. It can be said without doubt that chlorination is responsible for preventing many waterborne diseases, but chlorine also has a drawback. It can react to naturally occurring organic compounds in water to give potentially carcinogenic byproducts. It must however be mentioned that the advantages of chlorination exponentially outweigh the drawbacks, which is why it is the widely used in public water supply. The home filtration systems do not use chlorine, thus making it much more safer.

As we moved from boiling water to buying bottled water, the new trend seems to be shifting towards home filtration systems. But sadly, this new trend also exposes the same failings we aw in earlier trends. As we blindly trusted bottled water to be safe, many people think that water obtained from all filtration systems are safe, which may not necessarily be true. In essence, we are fully depending on the work ethics of the company that supplies these home filtrations. The government can barely regulate the bottling industry and seem to have no interest in regulating the filtration systems being sold in Nepal. In a country like Nepal, where the quality of drinking water is in general bad, companies would come in to provide means for self-reliance in drinking water. There are many brands of filtration systems available in the market. One could assume that the popular ones do deliver on their promises, but does that really matter when there are no government agencies to monitor and supervise these companies. Ultimately, it boils down to the same scenario: if we cannot really trust bottling companies to provide us with safe drinking water, how smart is it to trust water filtration companies that offer the same thing with a twist?