"tito lidi" should also be correct. lidé and lidi are both plural (nom) of člověk, or am i wrong?
Yes, you are wrong. Standard Czech nom. pl. is lidé. Lidi is non-standard. See the table in http://prirucka.ujc.cas.cz/?slovo=lidi
"Lidi" is colloquial and therefore considered as Standard Czech. It's also mentioned in the link that you posted (the first sentence below the table with declensions). For some reason, it's missing in the table.
It's on the table now.
Nope, only in accusative.
Is Potřebujou tito lidé vodu wrong grammatically?
It is a question word order.
Thanks! It seems sometimes I'm too eager to practice crafting sentences in a word order that I don't normally use that I forget what it actually sounds like.