Reverse Osmosis is not filtration

cartoon_filterWe regularly receive questions about whether a reverse osmosis (RO) system can eliminate a specific contaminant or not.  99% of the time, the root of the question is a misunderstanding of how a RO differs from a filter.

The best way we’ve been able to differentiate the two is to think of a filter like a sponge and RO like a wall.

Filters in one form or another capture the toxins suspended in the water as it passes through the filter media.  Sometimes it’s an absorption, like with carbon, and in others it’s more like a net.  With sediment filters or carbon blocks, you’ll see a micron rating.  The smaller the rating, the smaller the particles it can grab.

At least to a point, when the rating gets too small, the filters can clog up very quickly.  Which is a problem because many of the toxins we need to eliminate are smaller than filters can handle.

Which is why you need RO.

All ROs are built around the membrane.  It’s what does the heavy lifting and really cleans the water.  To keep it in good working order, it needs to be protected.  Which is why all ROs also have filters as a pre-membrane stage.  In our case with the MAXX, we use a 10 micron sediment cartridge first to get the largest particles out.  If not, these could quickly plug up the membrane. From there the water hits a very high-end wood carbon to take care of chloramines and chlorine.  Chloramines are particularly important because if they are not eliminated, the membranes can essentially be eaten away and become ineffective.

It’s at that point the water encounters the membrane and it’s .0001 micron rating.  Depending on the filter rating, that’s an improvement factor of at least 100,000x. Think of them like a wall that only lets the cleanest water molecules through…not the junk hanging on to them. That junk we don’t want to drink heads down the drain tube. If you’re more visual, here’s a spectrum to illustrate the vast differences between what a RO eliminates and your typical filter. {click image for a larger view}

RO_and_Particle_SizeNotice the size differences.  It’s enormous.  This is why it’s important to remineralize RO water.  It strips nearly everything out, including any beneficial minerals.  The membrane is highly effective and unless you are getting a cheapy one from China, they are all made by reputable companies (DOW, Filmtec, etc) and work nearly identically. A membrane is a membrane.

Which is also why the answer to that original question is so easy.  Yes, ROs take whatever you are concerned with out of the water.  [Before you ask, Yes, that includes biological contaminants and pharma residue/waste as well.]

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>