My horse lives out 24/7. She has an old bath in her field, which is filled from an IBC which catches rainwater from the field shelter. Last few days I've gone up, her bath has been full. I emptied it completely and wiped it all round with a dry cloth to get rid of all the gunk etc. Two days in a row its been full still. I've emptied it and re filled with clean water, but she's not interested. She's not dehydrated, but she has no other source of water. Weather is hot and dry, surely she should be thirsty?