How does reverse osmosis filter water?

Reverse osmosis (RO) filters water by using pressure to force water through a semi-permeable membrane, separating it from contaminants.

Understanding the Process

Reverse osmosis works by reversing the natural process of osmosis. Here's a breakdown:

Normal Osmosis: In osmosis, water naturally moves from an area of low solute concentration to an area of high solute concentration to equalize the concentration.
Reverse Osmosis: Reverse osmosis applies pressure to the concentrated side of the membrane (the contaminated side). This applied pressure overcomes the osmotic pressure and forces pure water from the concentrated (contaminated) side to the dilute (treated) side, as stated in the provided reference. The contaminants are left behind.

Component	Function
Pressure	Forces water against the semi-permeable membrane.
Semi-Permeable Membrane	A filter with extremely small pores that allows water molecules to pass through but blocks larger molecules like salts, minerals, and other impurities.
Concentrated Side (Contaminated)	The side of the membrane where contaminants are concentrated after water is forced through.
Dilute Side (Treated)	The side of the membrane where purified water collects after being forced through the membrane.

Pressurization: Water is pumped into the RO system, increasing the pressure on the contaminated water.
Membrane Filtration: This pressurized water is then forced against the semi-permeable membrane.
Separation: The membrane blocks the passage of most contaminants, allowing only pure water to pass through.
Collection: Purified water is collected on the other side of the membrane (the dilute or treated side).
Waste Removal: Contaminants that were blocked by the membrane are flushed away as waste.