I wore my old one out. Think it was 8 years old. I immediately bought another one. These units are awesome for keeping my dental work, teeth and gums CLEAN! Absolutely the best.
I previously owned a Waterpik. After I had a tooth extracted and a lot of other dental work I put salt in the water. It was soothing and refreshed the soreness but it damaged the tubing. I purchased another Waterpik and I am delighted with the way it cleans my teeth. This new model came with a toothbrush attachment and I like to use it before I use the other attachments.
I have one for 4 years. My husband has it in his bathroom and it was a pain to take care of my teeth, so I decided to buy my own and keep it in my bathroom. Use the pik and the gum stimulator 3 x 4 times a week. Also, use the toothbrush with or without water.