Reverse osmosis and ultrafiltration are two of the most powerful and effective water filtration systems on the market. Though both RO and ultrafiltration possess remarkable filtration properties, the systems do have key differences. From mineral retention, space requirements, to ease of installation and cost of maintenance, each system has unique advantages and disadvantages.
RO vs. UF
Reverse osmosis and ultrafiltration, commonly referred to as RO and UF, use membrane technology. The reverse osmosis system uses a semipermeable membrane that separates 95-98% of inorganic dissolved material from the water molecule.
The ultrafiltration system uses a hollow fiber membrane to stop solid debris and microscopic contaminants. UF is a mechanical filter, but it can filter water down to the superfine level of 0.01 micron, hence the name ultrafiltration. Ultrafiltration is a filter system, while reverse osmosis is a process where molecules are separated, filtering down to .0001 of a micron. Both membranes are preceded by sediment and/or carbon and proceeded by carbon filters.
Taste Difference
Taste-wise, ultrafiltration does retain minerals which affects how the water tastes. Users should expect a taste similar to a water used in a Brita filtered pitcher. Reverse Osmosis process eliminates virtually everything in the water including most dissolved minerals and dissolved solids (TDS) producing pure, mineral-less and flavorless water. The user experiences a taste most like purified bottled water.
Minerals and TDS
What RO removes:
Reverse osmosis eliminates the majority of the dissolved minerals in the water. Many people prefer this because they want their drinking water as pure as possible, and entirely free from minerals, salts, and dissolved solids. If you are looking for water with the highest degree of purity, RO has the advantage. If you do want to preserve minerals in your RO water, you will have to add a post-filter remineralizer.
What UF removes:
Ultrafiltration only filters out solid particulate matter, but it does so on a microscopic level. Because it has such a fine micron reduction capacity, ultrafiltration will filter out the vast majority of contaminants like sediment, chlorine, cysts and bacteria. However, it is not going to eliminate dissolved solids or salts. For people who want quality but prefer to retain minerals like calcium and magnesium in their water, ultrafiltration has the advantage.
Storage, Usage and Conservation
Another difference is that the ultrafiltration system can also operate on lower water pressures, while a reverse osmosis system needs higher water pressure or needs to be supported by a booster pump to increase the water pressure because of the small pore sizes. RO filtration cost more, requires more space and infrastructure.
| Factors | UF | RO |
|---|---|---|
| Water Pressure | Works well even with lower water pressure | Requires a water pressure of 35-40psi to function effectively |
| Drain | No drain required | Drain required |
| Space | No storage tank required and requires less space than RO. | Requires more space than UF due to storage tank |
| Production | Unlimited capacity/flow | Has a specified production capacity measured in gallons per day (GPD). High volume applications need to be sized correctly |
| Waste | No wastewater and no drain required | Due to intensity of filtration a percentage of water passes through membrane and the rest is flushed down the drain with contaminants. |
| Electricity | No electricity required | Where pressure is at 35psi or more, no pump and no electricity is required. Pump assisted RO systems require electricity; |
| Quality | Minerals remain in the water. | Everything other than water molecule is removed, including minerals. |
| Cost | $ | $$ |
| Taste | Filtered Brita pitcher taste | Purified bottled water taste |
| Limescale | Minerals that form limescale (calcium and magnesium) remain in the water. | Removes calcium and magnesium minerals, thereby eliminating limescale |
Reverse Osmosis is a cross flow filtration. The system creates two water streams through the membrane. One path ends up in a storage tank. Reverse osmosis makes water so slowly you have to store it to make it available. The tank takes up room under the counter. So, the RO storage tank could be a disadvantage for many people, as well as the slow filtration speed.
Ultrafiltration doesn’t require a storage tank. It literally hooks directly up to a special faucet. Both systems will require a dedicated faucet, they won’t run straight to your kitchen sink. But the ultrafiltration system comes through the filter at a gallon per minute with no storage tank need. Ultrafiltration does not produce wastewater, in fact, it can be used to make wastewater potable.
Which is better?
When strategically compared with other purification systems, UF is ideal for the removal of colloids, proteins, bacteria, pyrogens, proteins, and macromolecules larger than the pore size of the membrane. And a Reverse Osmosis water purifier system is ideal to remove both organic and inorganic compounds such as Fluoride, dissolved impurities, and Total Dissolved Solids (TDS) from the water down to .0001 of a micron, reducing arsenic, lead, parasitic cysts, copper, and more.
So, Ultrafiltration is not fundamentally different from reverse osmosis, except in terms of the size of the molecules it retains. The method you need depends on the quality of water you have at your premises and the level of water purification you need or want for yourself.
