This is a great gadget and combined with the Sonicare electric toothbrush, my teeth haven’t had any problems in years.
Alas, all good things must come to an end. After a few years of daily use, the fairly stiff hose got brittle and cracked.
A quick measurement of the hose got me the inside and outside diameter of it (Edit: 2mm ID x 4mm OD) and I ordered a food-grade silicone hose to replace it.
Disassembly of the WaterPik isn’t that hard. The handle is squeezed together and held with little pushpins. These will break when you pry the handle open so you have to hold it together with tape for testing. If testing goes well, you can superglue the handle back together. Given the superglue, this is a one-time repair.
Bad move. As it turns out, the hose is flexible enough that the pressure from the pump makes the hose expand with each pulse rather than force a strong beam of water out of the nozzle. You get a VERY weak flossing stream out of it.
Back to square one. I needed to find a hose with solid or rather, non-flexible walls.
Poking around the web for this hose, I ended up finding a far better solution!
A replacement handle!
In my quest to DIY a solution, I didn’t realize that a replacement handle for a common device was $7 from Amazon!
Two small screws on the bottom of the pump, and the handle was repaired and the WaterPik was working as new again.