How often does a landlord have to update an apartment? i.e. carpet?

Carpet, when it is worn out, not specific time. A carpet if property cleaned should last for years. The higher the upscale apartment of course the more often it would be replaced

What you get in a 250 dollar a month apartment is not the same quality you get in a 2500 dollar a month rental

We pay 875. Lived there for 19 years with the same carpet, our landlord said he is not changing it. It is really unsanitary, no carpet last 19 years no matter how good it is taken care of. I am writing him a letter stating that is against the law. Could he legally evict us because we need a new carpet?

If you have lived there for 19 years, you deserve new carpet. If you have a written lease they can not evict you for asking for carpet.

If you don't have a written lease they can evict you for any reason or no reason with a 30 day notice.

I would do my rental carpet about every 5 to ( OK I don't keep one much more than that)

I got rid of most of my carpet and put in wood floor, easier to fix when tennants mess it up. I wish I had someone that would stay that long, I have trouble with anyone over one to two years.