Water Bottle Pickiness?

[rattekonigin]

I changed the water bottle that I used with my boy rat about 3 days ago and I went in to check on the rats today and I noticed that he hadn't drunk one sip, it was still full to the brim, not even air bubbles at the top...since it had been 2-3 days he was visibly dehydrated, I gave him some pedialyte and changed his water bottle back to the old one and he's better now, drinking fine...but I am quite puzzled as to why he wouldn't drink from the other bottle...I checked for any blockages and there weren't any, and I can't find anything wrong with the bottle...has anyone had an experience like this? Very odd...