How to choose the right water filtration

When deciding what type of water purifier to install, you need to decide what you would like to remove from the water. Water purifiers may all look the same, but the inside composition of purifiers does vary a great deal, which affects their overall performance.

Taste & Odour / Chemicals

The basis of all purifiers is a substance called Activated Carbon. Activated carbon is initially derived from either coconut fibre or coal which is treated by being subjected to extreme temperatures and steam in the absence of oxygen. This process produces an extremely porous material on which organic molecules are adsorbed. The surface area of activated carbon is very high, with one kilogram of activated carbon having a surface area of around 112 hectares. Activated carbon can either be in a loose Granular form or a compressed tube commonly called a Carbon Block.
If your main concern is to improve the taste of the water and the removal of chemicals, either a GAC (Granulated Activated Carbon) or a Carbon Block cartridge will do the trick nicely. The quality, density and source of the carbon used in different cartridges varies enormously and effects the final performance. The cheaper cartridges will improve the flavour of the water, but the better cartridges will remove a wider range of chemicals as well as THM's*, and aluminium sulphate.
The hygienic life of carbon cartridges varies from 6 months to 2 years depending on the manufacturing process and the source of the Activated Carbon. Loose granulated carbon is generally less hygienic than a tightly bonded block cartridge. Some cartridges have silver bonded with the carbon to increase the hygienic life, as silver is a natural media which restricts many bacteria from breeding.

Heavy Metals

Most water purifiers use Activated Carbon as the principle purification media, but this will not remove the full range of potential Heavy Metals" from water. Most metals occur due to corrosion of copper pipe fittings by acidic or aggressive water. Other metals can be leached or washed into water supplies from industrial activities, although this would be rare in New Zealand. To remove metals such as lead, nickel, cadmium, mercury, arsenic, etc, you will need a cartridge which includes a material called KDF. KDF also increases the hygienic life of a carbon cartridge by up to three years, because it helps to prevent the growth of bacteria within the cartridge. KDF should not be used for untreated bore or roof water supplies. It should also be noted that because the KDF media exchanges Chlorine & Metal ions for Zinc ions, there can sometimes be a very slight bitter taste caused by the output of the zinc. A standard Carbon Block cartridge therefore tends to produce a slightly sweeter taste.

Minerals

Natural minerals in the water supply will not be removed by either carbon or KDF purifiers. This includes Fluoride which is a mineral. If you want to remove the added "Sodium Fluoride" you can either use a cartridge with "Actival" ( a fluoride specific resin ), or Reverse Osmosis. Please ask us for further details on the options available if interested.

Reverse Osmosis

Reverse Osmosis is really the “Rolls Royce" of water purifiers. These systems are good if you wish to remove everything from the water, including minerals and fluoride, which are not removed by a carbon-based purifier. They work on a principle of passing water over a semi permeable membrane. The water passes through the membrane while all chemicals and contaminants are washed down the sink. The water produced by these systems is near pure and similar to distilled water in content.  Reverse Osmosis uses a membrane that is semi-permeable, allowing water that is being purified to pass through it, while rejecting the contaminants that remain. The RO membrane uses crossflow technology which continually passes water across the membrane, thus flushing away the rejected contaminants. When the reservoir tank is full, water flow stops completely.

The reject ratio is normally about 75 to 85%, meaning for every litre of pure water collected, 4 to 5 litres of reject water is flushed away. While this may at first seem excessive, to produce 5 litres of pure water takes the same amount of water as used in a two-minute shower. Because of the ultra fine membrane used in RO, reject rates for nearly all contaminants are very high, typically around 96-99+ %, depending upon the contaminant and available water pressure.

Combined with the sediment and activated carbon filters, a quality RO system will remove fluoride, bacteria, protozoa and viruses, and significantly reduce organics, salts, metals, nitrates, pesticides and many more contaminants.

Easy to operate, with instant access to pure water, RO's require very little maintenance and have an operating cost for the average family of around P 1.00 per litre.

Distillers

Distillation is the process of boiling water and condensing the collected steam back into water again. In theory all the contaminants are left behind in the boiling chamber. Distillers are an option for people who want to remove minerals from the water. For drinking water the condensed steam should be passed through a carbon filter to remove any chemicals which are carried by the steam. The carbon filter also helps to improve the flavour of distilled water, which can have a bitter taste. Some chemicals do have low boiling points and so are actually evaporated with the steam. Distillers are easy to operate and are portable.


Trihalomethanes THMs

These are a type of chloroform caused by the reaction of chlorine with organic material.
THMs have been linked to causing bowel cancer in humans.