Building Biology | Which Type of Water Filter
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Which Type of Water Filter

Which Type of Water Filter

Did You Know

Most filter jugs do little more than improve the taste and odour of the water and should not be relied upon to remove contaminants. You do get what you pay for!

The source of your drinking water will determine the type of contaminants that are likely to be present and consequently the ideal water filtration system you should consider. Bottle-fed babies and young children are particularly susceptible to the contaminants likely to be in their drinking water as they drink up to four times more water for their body weight than most adults. For a discussion on the various contaminants present in tap, tank, bore/well and bottled water, refer to my book: Healthy Home Healthy Family.

I am often asked, “What’s the best water filter to buy?” and there is no simple answer to this question. This will depend on:

  1. How much money you are willing to spend.
  2. What contaminants you wish to remove which will largely depend on your source of drinking water: tap, tank or bore/well. The ideal filtration system for each of these sources is discussed in my book Healthy Home, Healthy Family.
  3. Whether you want a portable system (if you are renting or have a budget) versus a plumbed-in system.
  4. How much bench space you have.
  5. Your water pressure; the more units incorporated into your water filtration system, the more pressure you will require.
  6. Whether you want a point of use (POU) system ie one that is located at the kitchen tap or shower OR a point of entry (POE) system. Whole house systems are installed at your water meter and filter all the water coming into your home. Be mindful however that apart from their expense, these systems will NOT remove contaminants like rust, lead and copper arising from your domestic plumbing which is why I rarely recommend them.

Should I drink alkaline water?

There is insufficient evidence to validate the claim that drinking alkaline water leads to alkaline blood – indeed a narrow change in blood pH would result in death! Similarly drinking excessive amounts of alkaline water may affect stomach acidity and interfere with protein digestion amongst other issues.

Types of water filters for home use

Water filtration is a basic science – each type of filter media will be unique in its ability to remove certain contaminants – so don’t be fooled by companies making outrageous claims about their products for which there is little evidence. Water filtration systems will generally consist of one or more of the following:

  • Sediment filters are designed to remove particles such as dirt, rust, sand and clay and to protect carbon filters from clogging up too quickly. They can be made from a variety of different materials including polypropylene, polyester, cotton, cellulose, ceramic, wound string and glass fibre and come in a variety of micron sizes – 1, 5 and 10 microns. The smaller the size, the more effective they are at trapping smaller particles.
  • Carbon filters are sourced from organic matter such as wood, coal, bamboo, or coconut which are exposed to high temperatures in an oxygen deprived environment. They are then “activated” to increase their ability to adsorb contaminants by heating them with oxidising gas or other chemicals to break them into a fine powder. Apart from improving the taste, colour and odour of the water, carbon filters will effectively remove sediment, pesticides, petrochemicals, chlorine and its carcinogenic by-products (trihalomethanes). However they will only partially remove fluoride and heavy metals such as copper and lead. Their efficiency at removing contaminants will vary depending upon their micron size (0.5, 1, 5 and 10 microns), how effectively they are activated, and what they are derived from. In addition, their effectiveness declines rapidly with use as the absorption sites get used. If you wish to remove heavy metals, use a carbon filter impregnated with KDF. These filters need to be replaced before the manufacturer’s use-by-date as the effective life of a carbon filter is difficult to establish and bacteria will grow on the filter media.
  • Ceramic filters are cheap, long lasting and portable filters that effectively remove bacteria, chlorine, sediment and rust. However ceramic filters are not effective in removing heavy metals or pesticides, require regular maintenance (scrubbing to remove the biofilm), are slow to filter and can quickly clog up. Most ceramic filters consequently come with a carbon cartridge to remove organic contaminants such as pesticides and petrochemicals.
  • Ion exchange resin filters are used to remove heavy metals, fluoride and nitrates and to soften hard water. Whilst a variety of resins have been used including aluminosilicates, heavy metals, and synthetic resins like acrylic, the most widely used resin is styrene-DVB (divinylbenzene) gel polymer. However they do not remove sediment, pesticides, microbes or chlorine. Furthermore bacteria may grow on the resins and they may leak tiny resin fragments into the water supply which is why I don’t recommend them.
  • KDF filters consist of copper and zinc granules using an oxidation/reduction reaction to remove a wide range of contaminants including free chlorine, heavy metals and iron, as well as bacteria, algae and fungi. However it does not remove organic chemicals (pesticides, disinfection by products such as THMs) or parasitic cysts, and it can release contaminants back into the water once the filter becomes clogged. In addition they need to be periodically backwashed with hot water to remove the insoluble contaminants. Consequently KDF filters are not commonly used in household systems unless they are combined with a carbon filter
  • UV sterilisers are commonly used in aquariums and to sterilise medical equipment because they kill bacteria, algae and parasites and reduce cysts. They are not commonly used for water filtration in homes that rely on tap water as chlorinated water will effectively kill bacteria in the distribution system. However they should be considered as an additional add-on to a reverse osmosis system if you are ingesting tank water.
  • Reverse osmosis filters are a multi-stage system incorporating various sediment and carbon filters as well as a semi-permeable membrane. This system will effectively remove fluoride, pesticides, petrochemicals, chlorine and its by-products, asbestos, nitrates, radium and heavy metals (lead, copper, cadmium, chromium aluminium…). However they are expensive to buy, install and maintain, they will need to be plumbed in and they expend a considerable amount of waste water which will need to be diverted. Furthermore they require considerable under sink bench space. There is a concern that reverse osmosis water is ‘dead and acidic’ water. However most water found in lakes and rivers is slightly acidic (it absorbs carbon dioxide in the air to form carboxylic acid). As for the absence of minerals, my argument is that you shouldn’t be relying on water for this anyway. In response, many people alkalise their RO water which I do not recommend.

½ kg of activated carbon has a surface area of between 60 to 150 acres

An economical solution for people drinking tap water who cannot afford a Reverse Osmosis system will be to purchase a twin or triple stage portable or undersink system featuring a 1.0 micron pleated sediment filter along with one or two 0.5 micron activated carbon block filters. However if finances are an issue, a single stage system incorporating one dual function cartridge featuring a sediment filter and a 1 micron (or less) carbon block filter will still be of benefit. For suggestions on water filters for tank and bore/well water, refer to my book – Healthy Home Healthy Family.

Suppliers

These suppliers have been chosen because their filters are NSF certified, and because they don’t make outrageous and unsubstantiated claims about their products.

  • Aquasafe. Phone: 1800 636 135 Web: www.aquasafe.com.au
  • Clarence Water Filters Phone: 02) 6646 8565 Web: clarencewaterfilters.com.au
  • PSI Water Filters  Phone: 1800 305 579. Web: www.psifilters.com.au
  • Pure Stream Water Filters Phone: 1300 888 429. Web: www.aeoncp.com.au