I'm not certain about this claim that Tritrich comes from water. Parasites like Giardia are found commonly in water (just read the fine print on your city's water report for example) but Tritrich is thought to be transmitted by contact with infected cats as far as I know...
From a scientific article I just found:
"Thus, the present study provides no direct evidence for recent or ongoing acquisition of
T. foetus from other species (particularly cattle or swine), dietary sources (including ingestion of raw meat or toilet water), or exposure to international or domestic travel."
"In conclusion, the present study demonstrates a high prevalence of
T. foetus infection in purebred domestic show cats and a strong association between infection and the presence of diarrhea within the connected cattery."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC427826/
And fromhttp://fabcats.org/breeders/infosheets/tritrichomonas.html
"Infection is most commonly seen in colonies of cats and multicat households, where the organism is presumably spread between cats by close and direct contact. There has been no evidence of spread from other species, or spread via food or water."
The cure is hard on a cat but the side effects reversible, but obviously it is a severe enough disease to not take lightly. I've not had it (touch wood) here and hope never to!
I agree with Karenleigh, breeders that answer all your questions are a good choice. And the answers obviously have to satisfy you! I think papers should be standard, they cost very little and to me are part and parcel of selling a pedigreed cat. I also think people should see the contract and read it carefully before they agree to the terms and send money. I make my buyers wait until they see the contract even if they want to say yes right then and there!