How a Reverse Osmosis System Actually Works

Reverse osmosis is the deepest filtration technology used in homes. The membrane works at a .0005 micron removal rating, fine enough to pull out things ordinary filters can’t touch, including dissolved salts, metals, and many pharmaceutical residues. Here’s the simple version.

Start with osmosis

Osmosis is what plants do. Water naturally moves through a thin membrane from a low-mineral side to a high-mineral side, trying to balance the two. It’s a one-way trip in nature.

Now reverse it

An RO system uses your home’s water pressure to push water the wrong way through that membrane, from the dirty side to the clean side. The membrane is fine enough that water molecules pass through, but most contaminants are too big and get left behind.

The full stack

A real-world RO system has multiple stages, because the membrane is delicate and needs protection on both sides. A typical Filter Tech setup:

• Sediment pre-filter, keeps grit out of the membrane
• Carbon pre-filter, strips chlorine that would damage the membrane
• RO membrane, .0005 micron removal rating, the deep filtration step
• Storage tank, holds clean water for instant use
• Carbon post-filter, final polish before the faucet
• Post-alkaline cartridge, adds calcium and magnesium back for taste and balanced pH

What it removes, and what it doesn’t

RO removes the vast majority of total dissolved solids: salts, lead, fluoride, nitrates, arsenic, and many other contaminants. It does not sterilize water, pre-treatment is still needed for bacterial concerns.

Because the membrane strips minerals out along with everything else, Filter Tech includes a post-alkaline cartridge with our RO unit by default. It puts the healthy minerals, calcium and magnesium, back in after filtration, so you get pure water with the taste and pH balance of spring water. No flatness, no chemicals added.