Reverse Osmosis (RO) filtration removes which type of contaminants?

• A. It does not remove metals
• B. It removes dissolved metals
• C. It adds dissolved metals
• D. It only removes bacteria

Answer: (B)

Reverse osmosis works by using a semi-permeable membrane that blocks ions and larger molecules while letting water molecules pass through. Dissolved metals in water are present as ions, so they are rejected by the membrane and not carried into the purified water. That makes RO especially effective at removing dissolved metals from the water, along with other dissolved inorganic contaminants.

So the right choice reflects that dissolved metals are the type of contaminants RO targets, rather than merely removing bacteria or adding metals. While RO can reduce some microorganisms if the membrane is intact, its primary mechanism is rejecting dissolved ions like metals, not limited to bacteria.