why is il placed before tuo
Because that's how possesives work in Italian. There needs to be some form of "il" before the pronoun.
Check this link out :
Thanks for the help
why is the article for water not required here? I would expect it to be 'beve l'acqua'
I guess it's the same as in English. You can indicate which water (that water!) or just say it's drinking water if nobody cares where the horse is getting it from.
I agree with Lloyd... but generally Duolingo has been accepting l'acqua or acqua so it seems inconsistent