Types of Home Water Filtration/ Purifier System

Understanding your contaminants and what you need at home.

Contaminants which may be found in your residential water supply :

• Volatile Organic Chemicals (VOCs) such as pesticides, herbicides, pharmaceutical products, MTBE (methyl tertiary-butyl ether) and other chemicals. Research links certain VOCs to damage in the reproductive system, liver, kidneys and more.
• Heavy Metals - most commonly associated with poisoning of humans are mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), Boron and lead (Pb) 
• Endocrine Disrupting Chemicals are chemicals that may mimic or interfere with the normal hormones in the body and these chemicals are being found in increasing amounts in the water supply.
• Additives (Chlorine, Chloramines, Fluoride). Fluoride is added to the water for oral health. Fluoride has been linked to thyroid problems and other disorders when consumed internally.
• Rust, sand and decaying matter accumulates in aging water supply system ducts and pipes.
• Microbes; Cyst, Bacteria (eg: E.Coli) and viruses (Chlorine resistant Giardia, Cryptosporidium, etc.) and others
• Radioactive substances (Radon and Uranium, etc.)
• Selenium, turbidity, total dissolved solids (TDS), copper, trihalomethane (TTHM), aluminium, asbestos and others

Minerals which are beneficial for health: calcium, magnesium and potassium

The water has been treated and is safe for consumption according to SYABAS. Installing water filters at home can further reduce the contaminants in your drinking water. Filtering system manufacturers may test their own products, but a water filter isn't certified to remove contaminants unless it has been tested by an independent organization like NSF International or the Water Quality Association. Both have databases that consumers can easily search to learn more about the reliability of specific models. WQA Product Certification Areas.

Installing water filters after the water meter outside the house is not advisable by SYABAS. The use of water filters with very small pore size as in the case of ceramic filters / activated carbon filters can reduce the Free Residual Chlorine (FRC) content in treated water and also reduce the pressure of the water flowing into their house. When the water enters the tank and is stagnant, this can promote the growth of bacteria in the water, leading to skin irritation, etc. It is best to install them at the kitchen sink. Those who have already invested in water filters must carry out proper maintenance/ backwashing periodically as recommended by the manufacturer/ supplier to ensure the safety and quality of the water.

Type of contaminants Reduction Effectiveness with different water purification methods

1. Activated Carbon (AC) Filters

Activated carbon works via a process called chemical adsorption, whereby pollutant molecules in the fluid to be treated are trapped inside the pore structure of the carbon substrate. Active charcoal carbon filters are most effective at removing chlorine, sediment, volatile organic compounds (VOCs), taste and odor from water. They are not effective at removing minerals, salts, and dissolved inorganic compounds. Typical particle sizes that can be removed by carbon filters range from 0.5 to 50 micrometres (micron). In general, carbon block (compared to granular) filters are more effective at removing a larger number of contaminants, based upon the increased surface area of carbon.

Bacteria (mostly Non-pathogenic which cannot cause disease) can build up inside the active carbon filter. It is still recommended to replace or clean the filter at required time. Methods to kill or inactivate viruses, bacteria, protozoa and other pathogens: Boil the water, UV treatment, Chlorine.

Heavy metals are removed only by a very specific type of AC filter. Unless the manufacturer states that its product will remove heavy metals, the consumer should assume that the AC filter is not effective in removing them.

Water filters with carbon technology: Most of the systems in the market use a combination of activated carbon filtration and other technologies.

2. Reverse Osmosis Filters
The semi-permeable membrane used in reverse osmosis contains tiny pores through which water can flow. The small pores of this membrane are restrictive to organic compounds such as salt and other natural minerals, which generally have a larger molecular composition than water.

Pros:

• The membrane pores are restrictive to bacteria and disease-causing pathogens to avoid waterborne diseases. 
• Can filter/ reduce 

1. Radioactive substances like radium and uranium, 
2. Heavy metals such as mercury, cadmium, arsenic, chromium, and lead
3. Microbes; virus and bacteria, etc. 
4. Nitrate, fluoride 

Cons:

• The membrane is not very effective in blocking VOCs. For this reason, a more effective carbon filter must be used as a complimentary measure to provide safe drinking water. Such chemicals are the major contaminants of drinking water after municipal treatment.
• The removal of healthy, naturally occurring minerals in water.
• It generally wastes two to three gallons of water for every gallon of purified water it produces.
• Reverse osmosis is also an incredibly slow process when compared to other water treatment alternatives. 
• The are some precautions on drinking RO water though:
  1) Don't fill RO water in plastic bottle because of leaching effect. It's best to fill RO water in glass or stainless steel bottle.
  2) It's not recommended to drink RO water immediately after exercise. Isotonic drinks like 100plus can replenish the salt lost through sweat.
  3) Maintain a healthy diet or take nutrient supplements if you're to drink RO water.

Water Filters with RO technology: Coway, Bio Pure Elken, Kent RO    

3. Nano Filtration System
Same as Reverse Osmosis (RO) in removing impurities from water. Membranes are used to prevent contaminants from passing through. The difference is Nano allows beneficial minerals to pass but RO doesn't. Monovalent ions, the examples being chloride, sodium and other minerals, have no problems passing through the nano membrane, while divalent ions and the larger ions are removed.

Water Filters with RO technology: Cuckoo


4. Distilled Water System
Water distillers are the only water system that most completely and consistently removes the widest variety of contaminants. Instead of filtering the contaminants, a water distiller removes the water, leaving the impurities behind. One way to polish the water and improve the taste is to use a carbon postfilter which will add good minerals back into the water, which will restore the clean, pure taste. Relatively unpopular as a drinking water purifier.

Pro:

• Removes the widest variety of contaminants.
• Using distilled water in appliances (like espresso maker, humidifier, medical equipment) will reduce scale and mineral build-up. It will also discourage bacteria growth. 

Cons:

• Removes healthy, naturally occurring minerals in water which are required to maintain good health. 
• Makes the water tasteless.
• Slow process

Ref: freshwatersystems.com
https://www.freshwatersystems.com/t-steamwaterdistiller.aspx