Reverse Osmosis Vs. Ionization: Which Is Better and Why?

Both reverse osmosis and ionization are ways to remove hardness from water. Ionization uses sodium ions, while reverse osmosis use semi permeable membrane. Both the processes are used to purify water but in different ways and both of them can be used in different situations. Reverse Osmosis is better suited to treat water that is going to be used for drinking after purification and ionization is better suited to make completely soft water. Here are a few comparison notes on the two ways of removing water hardness.

Process of Purification:

When it comes to ionization, water is treated using Sodium ion resins. These resins attract the negatively charged molecules attached to calcium and magnesium salts. Calcium and magnesium is then collected on these resins and the water is left with sodium salts, which are harmless.

Reverse Osmosis, on the other hand, uses a semi permeable membrane that doesn’t just rid the water of hard salts but also removes contaminants and particulates. Reverse osmosis filtration removes metals, minerals, salts and particulates, but the system is limited by a slower flow rated due to which only 20% water is retained. However, with new advancements in technology, some reverse osmosis systems recover about 50% of water.

Cost Factor:

Water purifiers that use ionization technology are generally bigger and expensive as they are used to purify the water supply to a house. The need for an ionization technology water purifier is when the water is too hard to be used for anything.

Reverse Osmosis water purifiers are generally cheaper than ionization water purifiers as they are solely used for the purpose of drinking water. They sometimes do have added expenses like changing filters and membranes of the purifier.

Storage Capacity:

The water purified by Reverse Osmosis purifiers can be stored in 15-20L storage tank after purification. This capacity is regularly filled as the purifier purifies more water. This ensures that drinking water is available to the user 24/7.

Ionization water purifiers don’t generally need storage as they are directly connected to the water supply. They have a higher purification capacity though as they have to purify the entire water supply.


Both reverse osmosis and ionization water purifiers need a proper certified official for installation purposes. RO water purifiers are available as wall mounted, under-the-counter and commercial RO purifiers.  Commercial ones are expensive but come preinstalled and all you need to do is set them up with your water supply. The wall mounted ones and under-the-table ones need a technician to get installed.

Ionization water purifiers also come in two types- handheld and stable type. The handheld type needs to be plugged in every time the municipal water is supplied. The other type is one time installation and a technician does that. Once installed, you don’t need to worry about it.

Water Saving:

The ionization water purifier converts 100% of the hard water into soft water. Therefore, there is no wastage of water at all. The entirety of the water is purified using the resins of the ionizer. The reverse osmosis water purifier, on the other hand, purifies only 50% of water and the rest of the water is collected in some other container for other uses like cleaning and wiping. Therefore, no water is wasted, but still only 50% is purified as drinkable water.


In a nutshell, we can say that RO purification is always a better choice than ionization since it makes water absolutely safe for consumption. It would be a wise decision to invest in an RO purification system.

Post Author: Shyam

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