Below you’ll find the most Frequently Asked Questions we receive on reverse osmosis systems, covering everything from it’s effectiveness in filtering Fluoride, to the waste associated with RO systems, and how to get the minerals you need.

First, let’s review how Reverse Osmosis systems work. As we learned in middle school science class, osmosis is the process by which cells take in water--allowing it to pass through their membranes, while keeping other substances out. So when we talk about Reverse Osmosis for home water filtration, we’re discussing a system that draws inspiration from the way the very cells of our body filter water. An RO water filter uses pressure to push water that has a higher concentration of solids through a semi-permeable membrane, which allows the water to pass through, leaving the solids (contaminants) behind.

1. Are Reverse Osmosis systems effective in filtering Fluoride from the water? What about other common contaminants?

Reverse Osmosis systems are some of the most effective for removing fluoride, arsenic, asbestos, and heavy metals from drinking water. While effectiveness varies based on the system in use and the amount of pressure being exerted, independent testing shows that you can expect Reverse Osmosis systems, including the Aquaphor DWM (our most popular home RO system) to remove approximately 70% of those large-particle contaminants from drinking water.

2. How concerned should we be about waste from an Reverse Osmosis system? We’ve heard that a lot of water is discarded through the process.

One by-product of the filtration method in use with Reverse Osmosis systems is a large amount of waste water. This is also a large part of what makes these systems so effective.

As water is pressurized and forced through the semi-permeable membrane, the water with the lowest concentration of contaminants is able to move through to become your drinking water, leaving behind the water with the highest concentration of contaminants as waste.

Unfortunately, determining the exact amount of wastewater for a system is challenging and varies greatly based on a number of factors:
-Quality of the water going in (how high is the concentration of contaminants)
-Water temperature going in (if you’re on a well for example, a deep well will be
colder than a shallower well)
-How many pre-filters are in place in your home to begin with
-Your home’s water pressure

Because all of those factors are outside the control of the RO system, the amount of waste water can vary widely from home to home, even with the same system.

It’s important to recognize those factors, as many RO system manufacturers will base their claims off of the most ideal situations for their system which can vary from system to system as well---there is no standardization of the conditions they use for reporting their efficiency, which makes it very easy for manufacturers to put misleading information out there with their products. So be aware: A system that claims a 1:5 ratio may work better for your home than a system claiming 1:3, depending on your home’s water conditions.

For our money, we’ve become very partial to the Aquaphor DWM-101, based on its track record for consistently realizing a 1:4 drinkable water to wastewater ratio under a variety of home water conditions.

We’ve also known many intrepid DIY-ers reduce their waste further, by routing the waste water from their RO systems into outdoor rain barrels for landscape and flower bed watering, reducing the amount of water they would otherwise have to draw from the city (or their well) to complete the same tasks, if they DIDN’T have the RO waste water to utilize.

3. Reverse Osmosis removes over 95% minerals in the drinking water it filters. Is it safe to add those back in?

Delivering salts and minerals via water is thought to be one of the most bioavailable ways for your body to absorb those essential nutrients. Because reverse osmosis removes up to 97% of the salts and minerals contained in your water, it is essential to remineralize the water before drinking, so as not to lose a valuable source of electrolytes.

Often, you will need a separate system to remineralize water, but the Aquaphor DWM-101 includes a remineralizing tank in-system. It stores the RO-filtered water in a holding tank, which allows the Aquaphor system to provide stronger water pressure through the faucet. On it’s way to your glass, that pressurized RO water is passed through a mineralization cartridge that not only remineralizes your finished drinking water, but filters it a second time, delivering the purest water possible to your glass.

Have more questions about Reverse Osmosis filters or the Aquaphor DWM-101 Reverse Osmosis Water Filtration System? We’d love to hear from you! Drop us a line here, and we’ll get you an answer right away (and maybe even feature your question in a future Q&A article!).