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Carbon filters act like a sponge. They allow for high flow rates, meaning you can filter the water for your shower and washing machine. But once the sponge is full, contaminants break through.
Reverse Osmosis acts like a highly restrictive sieve. It provides the highest purity drinking water, but typically produces only a few dozen gallons a day and rejects 3-4 gallons of water down the drain for every 1 gallon of pure water produced. Therefore, whole-house RO is rare and expensive.
The most common recommendation from professionals is a hybrid: a whole-house carbon system to protect plumbing and reduce overall exposure, plus an under-sink RO system for pristine drinking water.