I purchased one of these water distillers so I could generate distilled water for a humidifier used in a grow tent environment. The unit I received works as advertised and produces about a liter per hour. It appears well built and was packed and shipped without incident. However, after about six days of use, the bottom of the vessel developed rust looking spots, which was unexpected, given that the inside container is supposed to be made with stainless steel. I use filtered water as the source, as it cuts down on any minerals that might be in your tap water that gets deposited as residue after the container is empty. In my case without a filter, our city water supply is hard water and has high pH levels. After the water is distillated, I checked with a PPM meter and the value is zero and it has neutral pH, which is what I would expect.Due to the rust spots, I contacted customer support and they were very understanding and very helpful and replaced the unit with a new device. I've been using the replacement unit for more than a week and do not have the same issues with rust spots appearing on the bottom of the container, so I assume the first unit might have had a manufacturing defect.Given the good customer support, I’ve rated the device with four stars.