Home Water Filters - How Do Water Filters Work?

Home Water Filters

Home Water Filters:

Have you ever wondered just how do water filters work? Home water filters have evolved into a compact unit or combination of units in answer to the ever growing number of toxins in the water supply.

Even if most of them are quite cheap, you have a right to know just what you are getting and the relative efficiency of each type.

Municipality Filtration materials:

Water filtered through sand, was probably the first type of filter used. They are very good for clearing the water, giving it a clean appearance. These are used extensively by Municipalities. Throw in some chlorine and that's what is piped to your home.

The two main types of home water filters are the gravity fed and the mains pressure fed systems.

Gravity fed:

These are free standing vessels which sit on a bench top. They normally have two chambers. Water is poured by hand into the top chamber. This chamber has a filter--often a ceramic 'candle' whose walls are impregnated with silver. The silver acts as a biocyde, killing off microbes. The inside of the candle is filled with activated carbon. 'Activated' simply means that the carbon material is processed in such a way as to increase its surface area, thus, increasing its adsorption surface area.

Purified water is gravity-forced into the lower chamber at a rate of around 1-2 litres an hour. These filters are quite efficient, can be pleasing to look at, and have the advantage of being portable--great for camping too. 

Mains pressure fed:

Many home water filters use materials contained within tubes or units. They may be positioned under the sink; on top of the sink; on the shower; at the fridge or at the point of entry of the water to the house. Mains water pressure, forces the water through, allowing only clean, pollutant free water to pass. The mediums used, determines what is taken out; what is left in, and by to what degree the water pressure is slowed.

The common materials used in pressure fed systems are:

Carbon, such as charcoal or coconut shell has been used in the past, and is still being used because it is an excellent filtering material. It works in three ways.

1. Unwanted particles don't pass through thus removing them from the water.

2. Toxic chemicals, eg chlorine are chemically attracted to the carbon's surface, effectively removing these as well. This process is called adsorption (collecting on the surface).

3. Number two above allows beneficial minerals such as calcium and magnesium, to pass, because their atoms don't bond with the carbon. These minerals along with others, give drinking water its pleasant taste.

Ion exchange: Water is passed over electrically charged resin spheres which exchange ions with substances in the water, changing them. Useful for softening water.

Membranes are used to filter out unwanted substances. Reverse osmosis systems use this by forcing untreated water through a semi permeable membrane. Their downside is that there is a lot of waste water; they don't remove chlorine and other chemical substances; are costly to run and also remove calcium and magnesium.

Others:

UV filters have the water pass through a Ultra Violet tube. Good for killing micro-organisms but don't remove other toxins.

Distillation methods, heat up the water and the cooling water collects in another vessel.  Good if you want demineralized tasteless water but not otherwise.

How do water filters work is a matter, then, of the filtering materials used and what home water needs to be filtered. The better ones employ more than one stage in the filtering process, as, only in this way, can all of the unwanted substances be removed.  There are many good brands of home water filters on the market, but as you will see below, the best need not be costly. 



By Douglas Jack 
Article Source: http://EzineArticles.com/2869619