Here’s the secret: RO doesn’t use a filter you can see, like a Brita pitcher. It uses something called a semipermeable membrane. That’s a fancy word for a super-thin sheet with microscopic holes.
These holes are tiny. I mean, laughably small. Only water molecules (H2O) can squeeze through them. Everything else—salts, metals, bacteria—is just too big to fit. It’s like trying to shove a beach ball through a keyhole.
But here’s the twist: water doesn’t just naturally flow through this membrane. You have to force it. That’s the “reverse” part of reverse osmosis. You’re pushing water against its natural flow. It’s stubborn, and we have to be more stubborn.
Pressure Makes Perfect
So, how do you force it? With water pressure. Your home’s water supply already has pressure, but for RO to work, it needs a little boost. That’s why most RO systems have a booster pump or rely on your existing line pressure.
This pressure shoves the water through the membrane. Think of it like a toddler pushing a toy through a fence. The toddler is the pressure, the fence is the membrane, and the toy is the water. The toys that are too big just stay behind.
How does a reverse osmosis water filtration system work? - Wolverine
And those big toys? They become what’s called concentrate or brine. Basically, all the nasty stuff gets flushed away down a drain. It’s the price you pay for perfect water.
