House um working in has 5 bathrooms. It is about 40 years old and has cast iron out to the main. Last year half of the line going out through the yard was replaced because of root damage. Everything was working fine but when they empty a bath upstairs the basement toilet gurgles. I've never known gurgling to be anything but a venting problem. The company that dug up the front half wants to dig up the rest for another 12k. I'm convinced it jus needs to be vented. Can I add a vent in the wall to help them? If so, does it need vented at the tub or at the basement toilet?

Did the drains gurgle before or is it a new problem. Gurgling could be caused by a clogged drain or inproperly vented drains. Did you have the line inspected with a drain camera. Each fixture must be vented If PA allow s wet venting you can use a 2 " pipe to vent all 3 fixtures if done properly.



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Gurgling is usually the result of trapped air being forced back up thru the internal trap of the toilet. I'd bet that it's a partially clogged sewer line.