Do I need vents?
I have a 1940s house and all of the bathroom plumbing along with the washing machine is vented with a single vent. The kitchen sink has its own. I've been told by plumbers that as long as you have one vent on the line, you're good...meaning if I added anything else, I just need to tie it into one of my existing drains. I don't know if that's the best advice or not but two plumbers told me the same thing.