Yes, don't be surprised if they don't give you many specific answers. Either they won't know exactly, or they don't want to accept full responsibility for you getting into a jam over some bad information.
Also, what you might want to do... get yourself equipped to filter and treat some seriously nasty stagnant water. I know that's not what you want to do. However, sometimes you have to do things to survive and not get sick.
One time in late season, a buddy and I got to our water source at about 9 p.m., and it was nearly dried up. All that was left was one pool of mosquito-infested brown water. So, I filled up a plastic jug with the stuff and mixed in a strong dose of iodine. After letting that stand, we poured it through a bandana, and then we boiled it.