There are two types of reverse osmosis systems: with tank and tankless.


The first type uses a small tank of about four gallons that contain two gallons of internal plastic bladder which holds the purified water before it dispensed. The remaining volume of the tank contains pressurized air that forced water to the faucet. To prevent purified water in the tank to develop a "flat" taste after it stay there for an extended period of time companies use in line carbon filters that are located between the tank and the dispensing faucet.


The tankless reverse osmosis system uses multiple TFC membranes. This is allowing purified water to be dispensed directly to the tap.


Tankless system is more compact than traditional system, does not require water storage and occupy less cabinet space.


However, Reverse Osmosis Systems is more expensive than traditional. Also, there are more costly membranes to replace. Another drawback of tankless system is that it require pressure at 40 PSI. For this reason, pressure booster pump maybe required.


Reverse osmosis system - uses pressure that forces unfiltered water to flow through the membrane and out of the low pressure side. All impurities that were not able to pass through membrane are wasted away to drain. There are two types of membranes that are used in reverse osmosis system to prepare home drinking water.


The second type of membranes is named "FTC". They are inorganic, and therefore not susceptible to bacteria grow. FTC membranes are more expensive. These membranes could be easily damaged by chlorine that is present in the water. That is why the reverse osmosis systems that uses this type of membrane utilizes a carbon pre-filter that absorbs chlorine and prevents TFC membranes from failure.