Water filters for your home
Water filters are usually recommended if you have a private water supply on your property with a high amount of sediment or is at risk of chemical contamination.
Many types of water filter are available for purchase or hire.
They range from the simple bench top style to sophisticated systems requiring special plumbing and electrical work.
How do water filters work?
Water filters work as a physical barrier that can block or trap debris (for example sand) and sometimes bacteria from passing through.
Generally, the speed of the water flow will depend on the size of the gaps in the filter barrier or membrane. A fine filter with the smallest gaps will mean a slower water flow. A clogged filter will also slow the water flow.
Careful consideration should therefore be given to the quantity of water required, and the time it takes to filter, before you buy a water filter.
Usually, water filters with a faster water flow are more expensive.
Will a water filter improve the taste and odour of water?
Several water filters currently on the market will effectively improve the taste and odour of water.
Filtration can remove tastes and odours whether they are naturally occurring or caused by a disinfection process.
Will a water filter remove bacteria?
Only a reverse osmosis water filtration system will effectively remove harmful bacteria.
The simplest way to remove harmful bacteria is to disinfect the water by chlorination or by ultraviolet radiation.
As some water filters remove biocides (substances that can control the growth of harmful organisms, such as chlorine), it is possible that bacteria will re-grow unless the filtered water is stored in a sterile container in a cool, dark place.
Some water filters may also allow bacteria to multiply to great levels on the filter pads if they are not maintained regularly.
In most circumstances domestic household water filters or ultra violet treatment systems will not make water safe in relation to amoeba unless you also disinfect with chlorine. Read more about amoebic meningitis.
Will a water filter soften hard water?
Some water filters will soften hard water. Hard water contains calcium and magnesium salts which results in:
the need to use more soap
a build up of scale on plumbing fixtures
a metallic taste to water.
Filter types available
Water filters that are currently available to consumers include:
polypropylene and ceramic
reverse osmosis and distiller.
The most sophisticated systems are reverse osmosis and distiller filters.
Polypropylene and ceramic filters
Polypropylene and ceramic filters function by removing particles from the water. Fibres are packed tightly together to form a fine mesh screen that physically traps and removes foreign particles from the water.
However, as these filters become clogged it is necessary to throw away the filter or cartridge and replace it with a new one. Some filters may also soften hard water.
Activated carbon filters
Activated carbon filters are most effective in removing chemicals such as iron, manganese, chlorine and hydrogen sulphide along with objectionable tastes and odours.
Some may also contain ion exchange resins that can soften hard water.
Polypropylene, ceramic or activated carbon filters should not be relied upon to disinfect water.
Reverse osmosis filters and distillers
Reverse osmosis filters and distillers are the most sophisticated systems. They are capable of removing bacteria and most residual chemicals, including minerals from a water source.
However, reverse osmosis and distillers are not effective in removing hydrogen sulphide (a gas with an unpleasant ‘rotten eggs’ smell) in acidic waters.
How much do water filters cost?
The cost of water filters vary considerably.
Some water filters are simple two-tiered jugs while others connect directly to the kitchen tap and are located either on or under the bench.
Reverse osmosis filters are the most expensive to purchase, install and operate.
Which filter should I use?
For discoloured water with fine particles of grit and other foreign material, a polypropylene or ceramic filter will effectively remove the sediment. It will not remove bacteria.
To remove naturally occurring or disinfection tastes and odours from water an activated carbon filter is more appropriate. It will not remove bacteria.
To remove chemicals and bacteria, a reverse osmosis or distiller system would be required.
In most circumstances domestic household water filters or ultra violet treatment systems will not make water safe in relation to amoeba unless you also disinfect with chlorine.