Looking for a movie about criminals that poison water.?

This is what i remember about the movie:

There were people that made a poison that somehow dry's people out
till they die. They had it in transparent canisters and wanted to put
it in the drinking water. the poison itself was red. They later were
in some underground water station or something where they hooked it up
to tubes so they could disperse it in the drinking water in the city.

I don't really remember any more.

Could someone tell me wich movie this is?