Nikken Pimag Waterfall Filter has been used. Last time used was over a year ago. Functions properly with a never used filter and set of rocks. There are some watermarks on the side walls as well as some smudges on the chrome and the grey plastic. It was cleaned and dried prior to putting it back in the original box where it resided the last year. But, I would still recommend cleaning it and flushing out the system by running water through the device 5 times prior to drinking. If you have any additional questions prior to purchasing don't hesitate to message me!