I assume this is electric or gas. 26 years is a long, long, time for a water heater to last. Usually they leak, or scale/sediment builds in the bottom of the tank, and they don't heat / recover well.

I would say it's time for a new one.

Alright!

if you have it from a long time ago of 26 years old so i think you have to buy a new one instead of repair the old one.

Here is a link that might be useful: Sub Zero Dallas

Most reading on the topics says 10-15 years for most electric or gas water heaters that are of the tank type variety. Can they last longer, yes. Can they last less, for sure. But, if you are trying to be preventative I would say replace it now to try and head off any issues. No matter how good it was made there is only so much they can do to prevent things from going bad (wearing out) in these types of units.

Replace it! My Mom's poured thousands and thousands of gallons of water into her crawl space. She didn't discover it until her electric and water bills went up by gazillions. After that, I decided to replace my 16 year old water heater. The guy said the relief valve crumbled in his hand. Boy, was I glad I had made the decision to get a new one.