Ultrafiltration and reverse osmosis are the most powerful water filtration processes available. Both have outstanding filtration properties, but they do differ in some key ways. In order to determine which one is right for your home, let’s better understand these two systems.

Is ultrafiltration the same as reverse osmosis?

No. Ultrafiltration (UF) and reverse osmosis (RO) are powerful and effective water treatment systems but UF differs from RO in a few significant ways:

• Filters out solids / particulates as small as 0.02 micron including bacteria. Does not remove dissolved minerals, TDS, and dissolved substances in water.
• Produces water on demand – no storage tank required
• Does not produce reject water (water conservation)
• Operates smoothly under low pressure – no electricity required

What is the difference between UF and RO?

Type of membrane technology

Ultrafiltration only removes particulates and solids, but it does so on a microscopic level; the membrane pore size is 0.02 micron. Taste-wise, ultrafiltration does retain minerals which affects how the water tastes.

Reverse osmosis eliminates virtually everything in water including the majority of dissolved minerals and dissolved solids. An RO membrane is a semi-permeable membrane that has a pore size of approximately 0.0001 micron. As a result, RO water is pretty much “tasteless” since it is free from minerals, chemicals, and other organic and inorganic compounds.

Some folks prefer their water to have minerals in it (which UF provides), and some folks prefer their water to be entirely pure and tasteless (which RO provides).

Ultrafiltration has a hollow fiber membrane so it’s basically a mechanical filter at a super fine level that stops particulates and solids.

Reverse osmosis is a process that separates molecules. It uses a semi-permeable membrane to separate inorganics and dissolved inorganics from the water molecule.

Storage tank

UF produces water on demands that goes straight to your dedicated faucet – no storage tank required.

RO requires a storage tank because it makes water very slowly. A storage tank takes up space under a sink. Additionally, RO tanks can grow bacteria if not properly sanitized regularly. You should sanitize your entire RO system including tank at least once per year.

Wastewater / Reject

Ultrafiltration does not produce waste water (reject) during the filtration process.*

In the reverse osmosis, there is cross-flow filtration through the membrane. This means that one stream (permeate / product water) goes to the storage tank, and one stream with all the contaminants and dissolved inorganics (reject) goes to drain. Typically for every 1 gallon of RO water produced, 3 gallons are sent to drain.

Installation

Installing an RO system requires making a few connections: the feed supply line, drain line for the reject water, a storage tank, and an air gap faucet.

Installing an ultrafiltration system with a flushable membrane (the latest in UF technology *) requires making a few connections: the feed supply line, drain line to flush the membrane, and to a dedicated faucet (drinking water applications) or outlet supply line (whole house or commercial applications).

To install an ultrafiltration system without a flushable membrane, just connect the system to the feed supply line and to the dedicated faucet (water for drinking applications) or outlet supply line (whole house or commercial applications).

Can UF reduce TDS?

Ultrafiltration does not eliminate dissolved solids or TDS dissolved in water; it only reduces and removes solids / particulates. UF may reduce some total dissolved solids (TDS) incidentally since it is ultrafine filtration, but as a process ultrafiltration does not remove dissolved minerals, dissolved salts, dissolved metals, and dissolved substances in water.

If your incoming water has a high TDS level (over 500 ppm) ultrafiltration is not recommended; only reverse osmosis will be effective to get the TDS down.

Which is better RO or UF?

Reverse osmosis and ultrafiltration are the most effective and powerful systems available. Ultimately which is better is a personal preference based on your water conditions, taste preference, space, desire to conserve water, water pressure, and more.

Drinking Water Systems: Ultrafiltration versus Reverse Osmosis

Here are some of the big questions to ask yourself in deciding whether an ultrafiltration or reverse osmosis drinking water system is best for you:

1. What’s the TDS of your water? If your incoming water has a high TDS count (over 500 ppm) ultrafiltration is not recommended; only reverse osmosis will be effective to get the TDS down.
2. Do you like the taste of minerals in your water for drinking? (If yes: ultrafiltration). Some people think RO water does not taste of anything, and others think it tastes flat and/or is slightly acidic – how does it taste for you and is that okay?
3. What’s your water pressure? RO needs a minimum of 50 psi to function properly – if you don’t have 50psi you’ll need a booster pump. Ultrafiltration works smoothly at low pressure.
4. Do you have a preference about wastewater? For each one gallon of RO water, about 3 gallons goes to the drain. Ultrafiltration produces no wastewater.