I live in a condominium and some of our units continue to have water underneath in the crawl space. We cannot detect any plumbing or rainwater as the source. How might we find the source or who in Huntsville, Alabama could we hire to resolve this for us?

Is there a chance the groundwater table is high enough to get into the crawl space? You might have the owner check for a clogged footing drain, but that would still be rainwater related, basically. Is there a chance that a nearby swimming pool is leaky? You might have a contractor dig some test holes around the perimeter in several places with a backhoe to 36" deep or more and look for hydraulic infiltration. A wetter hole might indicate proximity of the source. Good luck with this one.

First start would be to have all water turned off in each unit, and check the meters of each, and see if there is a leak.

That is the fastest way to determine if there is a leak in the supply lines.

A inspection can also go under ( if it is big enough) and inspect the drain lines to see if there are leaks in draiin lines.

DwightB suggestion on ground water sounds firm.

Maybe there is an underground spring in your area. Any streams or creeks anywhere around the condos with constant water in them?