Reverse Osmosis (RO)
Reverse osmosis is a filtration method that forces water through a fine semipermeable membrane to strip out dissolved salts, minerals, and most contaminants, producing very pure drinking water.
In reverse osmosis, household pressure pushes water against a membrane with openings so small that water molecules pass through but dissolved solids, salts, and most contaminants do not. What gets through is collected as purified product water, and the rejected minerals are flushed away in a stream of waste water. It is the most thorough point-of-use treatment a homeowner commonly installs.
Most home RO systems sit under the kitchen sink and feed a dedicated faucet and often the refrigerator line. They pair the membrane with sediment and carbon pre-filters that protect it, plus a small storage tank because the membrane produces water slowly. Whole-house RO exists but is far less common, since it needs large capacity, generates more waste water, and often requires re-adding minerals to keep the water from tasting flat.
RO removes far more than a carbon filter does, including dissolved solids that other filters leave behind, which is why it is the go-to for problem tap water and for homes that simply want bottled-quality water on tap. The trade-offs are some water sent to drain and periodic filter and membrane changes.
Talking to a contractor about this?
Run the project past a licensed plumbing pro first. Calls are answered around the clock and routed to a pro serving your area.
- Ion Exchange : Ion exchange is the process behind a water softener, where resin beads swap the calcium and magnesium ions in hard water for sodium or potassium ions.
- Backwash (Filtration) : Backwash is a self-cleaning cycle in which water flows backward through a filter or softener media bed to lift out trapped dirt and flush it to drain.
- Salt Bridge : A salt bridge is a hard crust that forms across the salt in a softener’s brine tank, leaving an air gap below it so the salt no longer dissolves into the water and regeneration fails.