OK the obvious question is why anyone would rig a coffee maker up to a faucet.....?
Much more reliable than having the wife wake up 15 minutes prior .. besides .. that would disturb my precious sleep.
Oh .. reread the post .. rigged up to a faucet??? still not sure what the problem was unless it was a very bad rig. Even the washers in kitchen bathroom faucets can sustain back flow pressure, and if their was an auto valve at the downstream side at the pot, the worst you could get would be equalized pressure on either side of the kitchen/bathroom faucet. Need more information that what was given to make a rational judgment.
Ours are that way at work. Filtered water automatically fills the pots.
It’s just like the water line hooked to the ice-maker in your refrigerator.