I understand what you mean, but only because I speak English. In Swedish, you would have to express that totally differently. I'd say Katten får inget or Katten får inte dricka av det, but there isn't one perfect counterpart to your English sentence, but several possible approximations.
Is it actually wrong to translate det with "this" instead of "that". My native language is German and we use "das" for both "this" and "that" (there are words to specify which one is meant, but mostly we just use "das") and "det" feels like its Swedish equivalent to me (so either that or this). But I keep getting wrong answers for using this instead of that in the translation.
In this course, this can correspond to det här/den här and detta/denna, and that can be den där/det där or den/det. This is a reasonable principle to stick with. In real life there may be some cases that are not so clear cut, but for the course, consistency is important.
I'm learning German too and I notice quite a lot of differences between our languages when it comes to determinacy/demonstratives. You don't use das hier or dies nearly as much as we use det här or detta.
The grammatically correct answer is "It is the dogs' water," and DuoLingo said "Almost correct!" and then said it should be "It is the dogs water," which is absolutely NOT correct in English. (I've made my living as a copy editor in English.) DuoLingo then goes on to say "Another correct answer: It is the dogs' water." So, dogs' is correct, and in some small way DuoLingo knows it, even if it's not willing to admit it to us.
No, that's not a word. For a better explanation, please see e.g. http://dictionary.cambridge.org/grammar/british-grammar/determiners/possession-john-s-car-a-friend-of-mine
I wrote "it is the dogs' water" and was corrected with a typo: it is the dogs water (no apostrophe) - THIS IS INCORRECT. A plural English noun used as a possessive has an apostrophe AFTER THE S. This is incorrect English, and must be corrected. Errors like this - in the English translation - are costing me loads of health, and making it impossible for me to make progress.
I think that it says dogs' because it means plural dogs. E.g The water belongs to the dogs. The dogs' water. Because in english, if a noun ends in "s" , it will have the apostrophe AFTER the s , with no s after the apostrophe m E.g Mary's book Jess' book. The dog's water. The dogs' water. Hope this helped.