[Greenbuilding] venting a gas water heater into ABS plumbing?

[Reuben Deumling]

As I am keen to minimize the number of perforations to my building
shell what would be the reasons NOT to vent my gas water heater into
the stack that vents my sinks? I certainly don't want to ignite sewer
gas, but what are the chances of that with such a setup? Or
precautions one might take to reduce the chances of it?

Thanks.

Reuben Deumling