"Is this water yours?"
Translation:Эта вода ваша?
I have to correct this. "Эта вода твоя" is fine, it means "Is this water yours?". But "Эта твоя вода" is not a sentence, it is more like a phrase "this water of yours". You can say "Это твоя вода?", this would mean "Is this your water?"
это = this (pronoun)
этот, эта, это, эти Х = this/these X. These words behave like adjectives which are used with nouns and agree with them in gender and number. "Это" here may confuse you, because it looks exactly the same as pronoun-like "это". However, in this category it is an adjective-like word used with neuter nouns.
- этот стол = this table
- это яблоко = this apple
- эта девушка = this girl
- эти дети = these children
- Это стол. = This is a table.
- Это яблоко. = This is an apple.
- Это девушка. = This is a girl.
- Это дети = These are children.
Hope this helps.