Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Short life span

I've had this waterpik for about a year and a half. After about 6 months the power diminishes and no longer charges well. Add another 6 months to a year and it no longer works unless I shake it to get the motor going. If you purchase it, I would do so with the expectation that it's going to last for about 1 year.