Apache & filesystem boundaries

With apache2 set up as local http server I get to test and prove my web pages before uploading them to my modest personal web site. But since at times I use different distros this leads to a lot of duplication and occasional loss because I don't know of any way to place one common http folder in a place where it could be used by apache on any of my installations. As far as I know apache will not let me configure with crossed filesystem boundaries, but what is THE reference filesystem when theoretically one could have as many partitions as directories under /?

To be specific I have 5 distros installed on /dev/sda partitions, how could I park the http directory on a partition on /dev/sdX? Is this possible at all?

TIA