I think that you are talking about Sand Ridge State Forest. Here is the link to the trail map, which has drinking water locations marked on it.

https://dnr.state.il.us/lands/Landmgt/parks/sitemaps/sandridge.pdf

Here is a link to my Caltopo map of the area:

http://caltopo.com/p/5N2S

This link will expire in seven days, so download the pdf while you can.

It's rare for water not to be found somewhere in the area, except in dry weather, but there are no obvious sources other than wells. This area is unusually sandy and may not have much surface water, it's hard to tell from the map.