My home was built in 1960 and has cast iron pipes. About every 2 months our toilet backs up and we have to call someone out to snake the pipes. We have had 2 different plumbers run a camera through the pipes and neither found any collapse or holes. They both told us to use cheap toilet paper that breaks down easily like Scotts, which we now do, but the problem persists. Here are some basic facts:
1. House built 1960
2. Cast iron pipes
3. Ground floor toilet
4. If you flush and the bathtub gurgles you can expect a flood within 24hrs.
5. Did my own little non-scientific test which consisted of dying a piece of toilet paper bright red with food coloring and sending my husband to the clean out to see if it came through or caught under the house. He says he saw it come through but now, just a few days later, it's backing up again. There is no water standing in the clean out, so I assume the problem is under the house.
Can anyone help me diagnose what 2 plumbers can't seem to? I'm wondering if it might be the ventilation stack. Thanks in advance.