Write an article based on this "Use the instruction manual. Buy replacement parts. Fix a drop in water pressure. Fix a leaking reservoir."
Each Waterpik unit comes with an instruction manual. If you lose it, you can download another copy on the Waterpik website. The Waterpik is an elaborate device with several parts that can break and require replacement. The Waterpik website includes a section where tips, accessories and replacement parts are available for sale separate from the main units. You should replace the tips every three to six months. A common issue is that the device sometimes loses water pressure. You can attempt to fix this issue before having to replace the device.  Ensure the black valve in the reservoir tank is inserted with the dome side facing up and the four-pronged side facing down. Fill the reservoir at least half full to support pressure. Confirm that the unit is plugged into a fully functioning electrical outlet. Regularly clean the unit by adding a few teaspoons of vinegar or chlorhexidine mouthwash to a full reservoir of warm water. Then drain the reservoir through the handle into the sink until it is empty. A reservoir leak is another common issue. You can attempt to fix this issue before having to replace the device.  Remove the black rubber valve from the water tank by pushing it out from the bottom. Run the valve under warm water and massage with your fingers. Return the valve to the tank. Ensure the dome side is facing up and the four-prong side is showing on the bottom.