[Krogers56]

Sink is backing up when the adjoin apartment turns on their sink faucet. The bathrooms are back to back on the third floor. Suggestions?

[massplumber2008]

Hi Kroger.

If you can access the common sink vent VIA a flat roof then you could snake down the vent and see if that solves the issue. If your roof is not flat, or the common sink vent is not readily accessible, then the next step would be to SNAKE the drain, OR use a pneumatic tool to clear the blockage... let me explain... ;)


If possible, you could try to rent an electric snake with a DROP HEAD (see image) on the end of the snake and then try to snake the drain from one apartment. Here, the drop head on the cable will helpto force the cable down the drain instead of going up the vent or going across into the other sink. This may take multiple attempts and you'll want to be sure the people in the adjacent apartment are home so they can work with you and make sure that the snake doesn't get tangled up in their drain/sink.

If that failed to work, you could try renting a GENERAL water ram (see image), plug off the overflows holes on both sinks, have your neighbor cover the overflow hole AND the drain with a towel on his/her side and then you would have someone cover the overflow hole for the sink on your side and then you would fill your sink with 1 inch of water and then you would insert the pneumatic tool into the sink drain (remove pop-up) and pump the tool to say 10 PSI to start and try to blow the blockage clear.

Those are two reasonable options and the tools should be easy to rent.

Try this, let me know if you have questions and then pop back as needed. We always like to know the result, OK?

Thanks... Mark

[Fr_Chuck]

You said apartment, then call the landlord, there will be a restriction in the drain line, that you both connect to.

[massplumber2008]

Agreed there... if this is an apartment and you damage anything it will be a real problem for you... contact landlord as suggested. If this is a condominium or town house and you are the owners, follow the advice as presented!

Mark