An RO (reverse osmosis) air gap faucet may leak for several reasons:

1. Loose connections: If the connections between the faucet and the water supply lines are loose, it can cause leaks. Check all the connections and tighten them if necessary.
2. Damaged O-rings: The O-rings inside the faucet can become worn or damaged over time, which can cause leaks. Replace the O-rings to fix the problem.
3. Clogged air gap: If the air gap is clogged, water can overflow and cause leaks. Clean the air gap thoroughly to ensure that water can flow freely.
4. Cracked faucet body: The faucet body can become cracked or damaged, which can cause leaks. In this case, you may need to replace the entire faucet.

Here are the steps to fix a leaking RO air gap faucet:

1. Turn off the water supply to the faucet.
2. Disassemble the faucet to access the internal components.
3. Inspect all the connections and tighten any that are loose.
4. Replace any damaged O-rings.
5. Clean the air gap to remove any blockages.
6. Check the faucet body for cracks or damage. If the faucet body is damaged, replace the entire faucet.
7. Reassemble the faucet and turn on the water supply.
8. Test the faucet for leaks by running water through it.

If the faucet continues to leak after attempting these steps, you may need to call a professional plumber for further assistance.