After a month of use. . .Update
Update (050719):  I have since received another unit from customer service and also purchased another unit from a different vendor. When using the flosser I now place the rubber plug into the charging port after learning my lesson with this unit.  I gave this one to my sister to try and advised her to place the small rubber adapter into the charging port when using it. I noticed after using the unit that calcium deposits developed inside the charging port. I cleaned it out, but it did not help my situation. The unit would not power on.<br /><br />Today, I received correspondence from customer service:<br /><br />Hello dear.<br /><br />Sorry for disturbing again.<br /><br />According to our technical team, the water flosser stop working probably because it get wet. But our water flosser are IPX7 waterproof. It wouldn't get wet even using it while taking shower. Could you check that whether you plug the cover for charging interface? Please remember to plug the cover while using.<br /><br />By the way, your review is really important for us. We would be grateful if you can remove it at your earliest convenience.<br /><br />Looking forward to your response.<br /><br />Sincerely<br />CSmile service team<br /><br />After the email, I upgraded my review to reflect 4 stars instead of 3. However, I am still not sure if the unit was defective or stopped working because of me using it without the adapter inside the charging port.  I advised customer service they need to update their instructions on the site and those with the unit to state to place the small adapter inside the charging port when in use.<br /><br />I will not be removing my review because it was my honest experience of using the unit. As I advised customer service I will update the review, but not remove it. I think it would be dishonest to do so because I was sent another unit. I am still not sure if the unit wasn't defective or if it failed because of the charging port not being protected. I mean this thing is supposed to be waterproof, right?<br /><br />Previous review: This water flosser works as described. If you haven't used one of these before, it is quite a different feeling against your gum line.  It fits well in your hand, but you can't effectively use it without mistakenly hitting the power or pressure mode buttons. Most of the time, I have to hold it on the bottom (by its base) because otherwise being able to maneuver it around can be frustrating because of the sensitivity of the pressure mode and power buttons before you can get it into your mouth.<br /><br />I cannot describe how many times I've had to wipe down my mirror and walls because I accidentally pressed the power button before I could get it into my mouth. Holding it at the base is the best way to use it.<br /><br />For two days I have not been able to use the water flosser because it stopped working. It has a full battery but yet will not turn on. I filled it with water and made sure the water tank was attached correctly...nothing. I placed it on my sink and walked away. I returned and could hear a noise of some sort. Upon investigation, the water flosser had come on and was squirting water onto the ceiling and light fixture in my bathroom. Crazy! I tried my darnedest to make sure it was off before leaving it alone, but it wouldn't come on. I assumed it would be another day of not working. However, it started working and sprayed my ceiling and light fixture before I could turn it off.<br /><br />I'm not clear why it is now working intermittently. It's not one that I would recommend because if it is waterlogged then I would have to question if it is really waterproof.  Because I am not careful with the amount of water that gets on the flosser because I thought it would not be a problem.  The water issue is about the only thing that I can imagine could have made it stop working or working on its own.<br /><br />**Update: I reached out to the seller regarding the issues with this device. The seller was very nice about replacing it. I was sent another one with no problems.  Customer service is excellent and aims to please. They are very serious about making your purchasing and user experience pleasant. They will do what it takes to make you a satisfied customer.
Rating: 4 stars