Super quiet. This thing will make you question whether it is actually working. It is a beast in more ways than one. I do highly recommend it only if you have the space under your sink; it's huge. I also recommend STRONGLY to have your car jack handy. Yes, car jack. It is heavy and unless you get it lined up the first time and are unlucky like me, you will need to hold it for a minute and it gets HEAVY! But seriously, I can't say enough about this machine. It's only been a couple months but seems to be handling everything we have thrown at it.