Technical Stuff

GAC - Granular activated carbon

One of the oldest and most used filtration media for removal of contaminants and odour. GAC does remove many common poisons such as chlorine and it’s by-products but has a short life as it is prone to becoming clogged with bacteria and once it is depleted, it allows everything to pass through.

Note: a media filter is like a bucket, when it’s full it overflows!
  'Softens' the water without chemicals or electricity.
  Reduces limescale (calcite) deposits in pipes & appliances.
  Removes existing limescale, coverts to aragonite (different crystal lattice)
  Enhances performance of soaps, cleaning agents and shampoos.
  Reduces power bills by keeping water heating elements clean and more efficient.
  Extends the life of water heating elements & appliances.
  No maintenance, electricity or chemicals required.
Contaminants are found in water in three basic states:
1. TDS’s -  Totally dissolved solids or salts.
     Molecular <0.2um organic or inorganic
     Lower temp = less dissolved

2. Un-dissolved Solids -  Sediments
           Particles from 0.2um up
           Finest are clays which in some cases can go down to molecular level, and remain as TSS’s (Total Suspended Solids)

3. Dissolved gases - Oxygen, carbon dioxide, methane, nitrogen, hydrogen sulphide etc.
GAC/KDF media can remove up to 99% of water-soluble cations (positively-charged ions) of heavy (active) metals. When filtered through KDF media, soluble lead cations are reduced to insoluble lead atoms, which are electroplated onto the surface of the media. NB: other heavy metals bond to the media in this same way. KDF process media kills bacteria by direct electrochemical contact and by the flash formation of hydroxyl radicals and hydrogen peroxide, both of which interface with a microorganism’s ability to function.

  Effective removal of a wide range of contaminants
  Extend life and efficiency of carbon (GAC) filters
  Remains effective at higher water temperature
  Outperforms silver- impregnated carbons (silver is not considered safe)
  Removes the total dissolved salts (conductance) or total dissolved solids (evaporated)

History - As with many inventions, combining copper and zinc to produce an electro-chemical reaction to remove free chlorine was an accidental discovery by Don Heskett in 1984, which lead to the creation of KDF Fluid Treatment Inc.

Function - Using an electro-chemical process know as redox (oxidation-reduction), KDF media is zinc-copper alloy that removes up to 99% of free chlorine, heavy metals, silver, aluminum, cadmium, copper, iron, nickel, zinc, lead, chromium, barium, hydrogen sulphide, radon selenium, trihalomethanes, manganese, mercury, chloroform, trichloroethane, lindane, pesticides, fungicides, bad taste and odours.

KDF extends the life of the GAC by up to 4 times.
The sediment filter is a graded or wedge type filter that starts at 20 um (Human hair is 50-100um diameter) and reduces to anominal 1um.

This extends the life of the filter as the larger particles get trapped within the first few millimeters.

One micron (um) does remove many bacteria and all protozoa that are generally around 7um in size.

Some of the smallest particles like clays etc. will get through, eg: lake water in the Otago area is blue due to fine blue clays.
Rural systems are different to the urban system

A. Rainwater - Most NZ county by-laws state a sterilization system is mandatory with any new installation, where water is collected from any roof or open surface.

What to do - Submit a description, flow rates, etc. and any test report to us for a quote.

A UV system is mandatory and any indications that there may be heavy metals present should be noted ie: lead flashing on iron roofs.

B. Groundwater - A lab test is required to establish the water biochemistry and chemistry. The system subsequently supplied by us will be customized (as best as possible) to address as many issues as possible.

What you should do -   If using rainwater and groundwater you will need a UV system
Talk to us about a lab test, so we can make accurate recommendations to suit your needs.

Caution: Groundwater chemistry is complex and there is no ‘standard’ answer, as there can be many TDS’s and gases in groundwater that change the way it behaves upon reaching the surface.