SC had rules requiring collection, if over so many gallons of water were used. The limit for reclamation was pretty high. The state and city was sensitive to fundraiser car washes. These rules helped out. I found this information on the SC health and environmental control web site. Perhaps TX has something similar to use. I had to contact the health dept with specific questions but I had a little insight before the call.
Maybe some diggin in here
TCEQ Publications - Texas Commission on Environmental Quality - www.tceq.state.tx.us. Checkout the water link at the top.
Specifically for big car washes.
Environmental Rules for Car Washes - Texas Commission on Environmental Quality - www.tceq.state.tx.us Haven't read yet.
It's looking like TX is gonna pretty stiff with reclamation rules. Just like CA. You could fail conservative and get a collection mat.
Mobile Wash Mat - DE1900
Hope this helps. Good luck, you'll need it dealing with govt agencies.