Toilets & Sinks Draining Through Shower
Hi,
I have a full downstairs bathroom w/ shower as well as an upstairs one pretty much above the lower. I have just recently noticed the sound of draining water through the downstairs shower drain every time the upstairs shower, sink or toilet drains as well as when the downstairs sink or toilet drains. I don't recall hearing this before. There is no backup. Is this possibly a venting issue or a clog?
If a venting issue, would it be a roof vent (2 story home) or the sewer vent on the ground level? And would I use a snake, compressed air, etc?
Any help would be appreciated.
Thanks,
TS