A Guide to Water Purifiers
As a vital resource for all life, access to pure water is essential. The knowledge of what type of filter to use can ensure health and longevity. And for this reason, it is important to select the right system of filters based on the source of the drinking water. Let's look at all three possible sources: municipal water, ground water, and water from mixed sources.
Wherever the water may come from, it is imperative to consider the TDS (Total Dissolved Salts) present in the water. This greatly influences the type of filter chosen. TDS is measured in ppm (parts per million). The illustration here gives a general guideline on the range of TDS, depending on the source of the water.
The most common constituents of TDS are calcium, phosphates, nitrates, sodium, potassium, chlorine and iron.
Based on the TDS rating of the water, look for one or more of the following: UF (Ultra Filtration) Technology, UV (Ultraviolet) Technology, RO (Reverse Osmosis) Technology, EAT (Electro Adsorption Technology), a combination or a Universal Water Purifer. After this, choose which purifier unit - electric or non-electric. Note that some filters require electricity to function. Let's look at all the filters available.
- Only type of water purifier certified to remove cysts
- Works without electricity
- Does not remove dissolved impurities
- Not an absolute barrier to viruses
- Disinfection recommended
It is suitable for use with water that has low TDS. Most gravity-based purifiers have a water storage tank that can store up to 13 litres.
- Does not alter water chemically
- Sterilised microorganisms are not removed from the water
- Does not remove dissolved organics, inorganics or particles
- Fast disinfection process
UV energy penetrates the microorganism’s outer cell membrane, passes through the cell body and disrupts its DNA, preventing reproduction.
Ultraviolet light is invisible to the naked eye and can best be described as a form of invisible radiation.
- Most convenient and effective method
- Effective when TDS (Total Dissolved Salts) rating is between 200 and 2000
- Reduces the hardness of water which is caused by excessive calcium & magnesium salts
- Purifies water of contamination caused by fluoride or other harmful chemicals and heavy metals, such as arsenic, lead, mercury
It works by squeezing water through a semi-permeable membrane, which is rated at 0.0001 micron (about 0.00000004 of an inch). This is the technology used to make bottled water. It is also the only technology capable of desalinating seawater, making it drinkable.
EAT purification technology has five advanced stages of purification. It is available in electric and nonelectric variants, and some have storage tanks. It is ideal for water which has less than 500 ppm (parts per million) TDS.
- First Stage - External Prefilter removes sand, silica, silt, dirt and dust present in water and also enhances the life of the water filter
- Second Stage - Mechanical Filter removes dirt and other suspended solids through a sediment mesh
- Third Stage - Electro Adhesion Filter removes impurities that carry a negative charge, removes disease-causing cysts, germs such as bacteria and virus
- Fourth Stage - Ion Exchange, which has specially activated carbon granules, removes heavy metals like lead and arsenic
- Fifth Stage - Electro Adsorption removes harmful chemicals like chlorine, pesticides and endotoxins
These water purifying units have storage tanks to store water after it is purified through sediment and activated carbon filters. Useful in places where water supply is unreliable.
Made of food-grade plastic, these water purifiers are directly fixed to the water tap. They are usually candle-shaped filter units that consist of a resin filter that has to be replaced once a month. They’re UF and Activated Carbon filters that run without electricity.
There are also personal water purifiers - water-bottle-sized, optimal active units that attract and remove waterborne pathogens. They are great for pure water anywhere, anytime, owing to their traveller-friendly size.
Electric water purifiers are always connected to the water supply and run on electricity. They use sediment filters and activated water filters with UV or RO purification systems, which require electricity.
Electrical units are also available without a storage tank. This type is quite popular - many units through the '90s were of this type. Useful in places that have a steady supply of electricity through the year, the filtration quality is the same as of those with storage.
Using built-in pumps, purifiers can even draw water stored in a vessel, making them ideal for areas with no running water or low water pressure.
For places that have frequent power cuts or unreliable water supply, consider buying a purifier with a storage tank. This will ensure access to pure, drinkable water even without electricity – as long as some water is stored in the tank.
Also, if you have a large family, a purifier with a storage tank is better for continuous supply.
TDS controllers are often found in RO, UV and UF purifiers. The TDS regulator constantly senses TDS levels and selects the best purification process.