My RO/DI came set up for an under sink installation as well. I went to Lowes and found that they have about 1000 different adapters in the plumbing area where they sell the smaller tubing. I was able to find an adapter for a garden hose there. It took me a while find what I was looking for, but they had it. It goes from a garden hose down to a 1/4" compression fitting which worked for me. I'm not sure about a faucet adapter but it might be worth a try.