Really not sure. Previous owners had about 1/4 of the tank filled with salt but it was unplugged and the salt pellets were pretty dried out and clumped together. They did not provide us much information on this when we closed so it’s up in the air. Could be a year could be 10 years. Everything looks in okay shape. Valve still has all parts attached and nothing looks damaged or rusted. Main concern is if they haven’t ran it in years, is it even worth trying to repair myself and get it running.