Filter Pore Size/ Micron Rating
Pore Size. Water filter with bigger pore size allows more contaminants to pass through. Filter with smaller pore size is able to block and eliminate more impurities in the water. The membrane used in reverse osmosis filtration system contains tiny pores the size of approximately 0.0001 micron. It can eliminate most small particles such as heavy metals, radioactive substances, viruses. For example, the Covid-19 SARS-CoV-2 virus has a size range of 0.06 microns to 0.14 microns.
Generally, Activated carbon water filtration systems have rating of about 0.2 – 0.5 microns. They are not effective in removing viruses and can remove some heavy metals and radioactive substances. The smallest microplastic reportedly found in the oceans is 1.6 microns. Both activated carbon and RO filters can effectively eliminate mircroplastics, sediment and rust.
An ultrafiltration system has a pore size around 0.01 micron.
Type of Dispensers
Water Filter Dispenser. Depending on the kitchen space you have and the functions you are looking for, there are different types of dispenser to choose from.
The under sink filters save counter space but you may need a plumber to install the tubing and dedicated faucet. Counter top filters are easier to install.
The instant hot water filter dispenser with other features is highly preferred for its convenience and multi-functionality.
Activated carbon works via a process called chemical adsorption, whereby pollutant molecules in the fluid to be treated are attracted to the surface of the carbon layer and trapped in the pores. Activated carbon has very strong physical adsorption forces and high porosity with very large surface area. Five grams of activated carbon can have the surface area of an entire football field. When a carbon filter’s pores are filled, the accumulated particles start to separate from the carbon and flow into your water supply. Therefore, you should replace your carbon filter every six to twelve months.
Volatile Organic Chemicals (VOCs) such as pesticides, pharmaceutical products, MTBE and other chemicals, are linked to damage in the reproductive system, liver, kidneys and more. VOC molecules are very small, which have diameters measured in picometers. Chlorine is added to the water supply to kill bacteria, parasites and viruses. They can be effectively removed by carbon adsorption process. By itself, RO filters are not effective at eliminating VOC and chlorine, a more effective carbon filter must be used as a complimentary measure.
An applied pressure is used to push the water through the semipermeable membrane used in reverse osmosis filtration which contains tiny pores the size of approximately 0.0001 micron (100 picometer), through which water can flow and are restrictive to compounds such as minerals, microbes which generally have a larger molecular composition.
Reverse Osmosis (RO). Though highly effective in the elimination of very small particles, Reverse Osmosis filters also remove all healthy, naturally occurring minerals in our drinking water. It generally wastes two to three gallons of water for every gallon of purified water it produces and is a slow process compared to other water treatment methods.
2L waste water for 1L purified water
Choose the water filter which has been tested and certified with the features that you are looking for. Independent organizations like NSF International or The Water Quality Association (WQA) have databases that consumers can easily search to verify the type of contaminants/ components each model has been tested for.
Heavy metals are removed only by a specific type of Activated Carbon filter. Unless the manufacturer states that its product will remove heavy metals, the consumer should assume that Carbon filter is not effective in removing them.
For example a hybrid filter that made out of activated carbon and whey protein fibres can eliminate heavy metals such as lead, mercury, gold and palladium; radioactive substances, such as uranium or phosphorus-32; highly toxic metal cyanides from water.