And another lot of water is in the seas. And a third lot of water is in plastic bottles.
I would rather say "There is a lot of water in the rivers."
"There is lot of water" is absolutely unidiomatic English. Alternatives are "a lot of" or "lots of" but a and lots were not options.
I said "much" instead of "a lot" (after reading in another discussion thread that someone had been marked wrong for saying "a lot" instead of "much") but this was rejected - should I report it?
I dont think "much" is technically wrong in English, it just sounds unusual, a bit like you are speaking English from a bygone era!
I was given this sentence in a "Type what you hear" task but there was no audio :(