500 albums in a basement flood--worth saving?

500 of Anything is more than 'a couple of hours' to do properly...
...especially 'manually'....

Triage time:  Decide what you really want to keep.
Take pics of the covers if they're not too shot.
Labels too, unless you've got the leisure to drag the net for the info.
Do 10~20 a day.  You already have a life, and you're not a pro curator.

Used to live in Houston....been there, did that.
Fortunately, not that many....

Sorry I missed the record cleaning machine mention. Agreed long time. I hate record meaning machines tbh - it’s annoying but you can actually do better with a very soft toothbrush, Dawn soap and a dish drying rack. Sleeves being ruined is a big bummer, sorry to hear about this!

Keep the records. I had minimal flood damage to the covers of records stored on the bottom shelves in my music room. If I would have had each album in clear plastic outer sleeves there would have been no covers wet and no damage. Fortunately I had most of the records themselves in Mo-Fi plastic inner sleeves and not paper sleeves. I never liked paper sleeves. Every wet-cover-record played perfectly. My wife toweled off each of a couple hundred lps and opened every gatefold lp and set out all lps all over the house to dry out. She is golden! After drying out the outer covers there was minimal damage. Keep those records!😁

What were you thinking when you opened the steel door?

I lived in Miami for 5 years. Hurricanes cause massive flooding and due to the humidity it is the mildew capital of the USA. I fortunately lived with the cockroaches on the 17th floor but a friend lived in a single story house and he kept his records sandwiched between two cabinets on the floor. Needless to say what happened. By the time the water had receded the stench of mildew was already present. We moved all his records to my flat where we removed them one at a time sprayed them off with tap water, used a spray bottle to rinse them off with distilled water, dried them off gently on a cotton towel then let them air. We stacked them gently in groups of 40 and wrapped them in plastic wrap with a few small holes for aeration. There were maybe 300 records. Eventually he got new sleeves and blank covers for them. Fortunately, his gear was up in the air. The records sounded fine.