water question

[Rubytuesday]

can a horse drink too much?
This goes back to the filly with diarreha and the fact that when I watered her this evening she drank 28litres of water and electrolytes in 3 hours. I know if I went back out to see her an hour later she would drink another 16 litres.
Like I mentioned before she becomes firm overnight and in the day she gets loose again and I could not figure it out. I believe it is because she drinks so much during the day and at night she stops drinking, but she does have access to water at night.
Her insides have a chance to dry up at night and almost have a chance to become normal at night.

If a horse has diarreha would they not have it all the time no matter how much water they have in their system?

I believe she is trying to drown herself.