Which Is Better—Reverse Osmosis or Ultrafiltration?

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By Sheila Anthony

You want a cooler or filtration system, but you can’t decide between a reverse osmosis system or an ultrafiltration one. What’s the difference anyway? And which is better? We lay it out in this quick 5 minute read.

How Does Ultrafiltration Work?

Ultrafiltration (aka UF) is a barrier method of filtration and is typically the final stage of a 3-stage process. Incoming water enters the ultrafiltration cartridge tubes which are perforated with pores 0.01 of a micron in diameter. The flow forces the water through the pores, and anything larger than 0.01 of a micron is blocked from moving on to the fresh-water line that leads to a dedicated faucet at the sink.

Notably, ultrafiltration removes solid particulates only, not dissolved solids.

Set up is quick and easy with ultrafiltration. No wastewater is created, so there’s no hole for a wastewater line that needs to be drilled – something that may be much more convenient for renters.

The ultrafiltration filter needs to the changed every 6 to 12 months, depending on use and the home’s water quality, and the filter works very efficiently even under low water pressure conditions.

Here are some of the most common contaminants that ultrafiltration removes:

  • Bacteria
  • Copper
  • Cysts
  • Lead
  • PFAS
  • Pharmaceuticals
  • Protozoa
  • Viruses

How Does Reverse Osmosis Work?

Reverse osmosis (aka RO) is also a barrier method of filtration and is typically the third stage in a 4-stage process. Reverse osmosis leverages natural osmosis by exerting pressure on the incoming water and forcing it the other way through a membrane with pores 0.0001 of a micron in diameter. Contaminated water or brine is removed through a wastewater line connected to under-sink plumbing while the purified water moves on.

Notably, reverse osmosis not only significantly reduces solid particulates, it also reduces total dissolved solids (TDS). In both cases by 99.97%.

Setting up a reverse osmosis system is a little more complicated than ultrafiltration. As mentioned, reverse osmosis produces wastewater and, therefore, requires a connection to the home’s wastewater pipe. Also, typical wastewater-to-purified water ratio is 4:1. However, the Brio G20-U under-sink filtration unit offers a compelling 2:1 wastewater-to-purified water ratio.

Because RO filtration requires a dedicated wastewater line, it may not be an option for renters if they cannot get permission from their landlord to install one, as it requires drilling a hole in the appropriate under-sink pipe.

Like the ultrafiltration filter, the reverse osmosis filter needs to the changed every 6 to 12 months. Unlike ultrafiltration, however, reverse osmosis filters need higher water pressure to function effectively. For instance, the excellent Brio Moderna Reverse Osmosis Water Cooler requires a water pressure of 58 to 116 psi (pounds per square inch).

The significant advantage of reverse osmosis over ultrafiltration is its ability to reduce dissolved minerals from the water, which is something ultrafiltration wasn’t designed to do.

Bolded are just some of the contaminants reverse osmosis blocks in addition to the particulates that ultrafiltration can reduce:

  • Arsenic
  • Bacteria
  • Calcium
  • Copper
  • Cysts
  • Fluoride
  • Lead
  • Magnesium
  • Nitrates
  • PFAS
  • Pharmaceuticals
  • Protozoa
  • Sulfates
  • TDS (like chloride, salts/sodium, and potassium)
  • Viruses

Reverse osmosis, in short, filters out just about everything. It’s perfect if you have particularly hard water that’s wreaking havoc on your pipes and fixtures, as it has a remarkable ability to block dissolved solids like calcium and magnesium.

So Which One Is the Right One?

Choosing between ultrafiltration and reverse osmosis is a personal decision. If you live in more rural area with high levels of arsenic, you’ll probably want to consider a reverse osmosis system. This would also be the case if your appliances and plumbing fixtures are being hard hit by calcium scale.

On the other hand, if you live in a suburban or urban environment where arsenic isn’t a concern, but lead might be, and you also don’t mind calcium or magnesium in your water, then ultrafiltration may be the better choice.

Assessing your health needs, plumbing needs, and living situation is the first place to start when deciding which filtration system is the right one for you. It’s comforting to know you can’t go wrong. Both are excellent and will result in fresh, great-tasting water.

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