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.

Sources of Water

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.

UF (Ultra Filtration) Technology - Gravity-based Water Purifier

· 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.

UV (Ultraviolet) Technology

· 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.

RO (Reverse Osmosis) Technology

· 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.