Old house plumbing question: sink P-trap located below floor
Bought an 1880s house a few years ago and discovered one of its quirks: the bathroom sink P-trap is not under the sink. The drain goes straight through the vanity/floor, and the actual P-trap is located in the basement below the bathroom floor.
This setup has worked fine until recently. The sink now drains extremely slowly/almost not at all, and we’ve tried all the normal DIY fixes:
- plunger
- drain cleaner
- hand snake from above
- removing/cleaning the stopper
Nothing has worked.
We’re calling a plumber, but I wanted some opinions from pros first.
A contractor previously told us that relocating the trap under the sink (where it would normally be) would be a “massive job” and quoted around $10k.
We’re planning to replace the bathroom vanity soon anyway, so I’m wondering:
Q: Is moving the P-trap into the vanity actually a major project in an old house like this?
Q: Is there any reason this setup needs to stay the way it is?
Q: Does the current configuration suggest venting issues or other likely problems?
Photos attached:
- current under-sink setup
- basement view showing the trap below the floor
Appreciate any insight from people who deal with old-house plumbing regularly.