I share a room in an old house. In the first few weeks I put no more than 1/2 cup of grease in the garbage disposal and chased it with hot water.

The sink has 2 basins. Now when we run water in either one, the water came back up the other - much dirtier than it went down.

The landlord says that my little bit of greased caused this problem. I suspect that the blockage has accumulated over time - a time much longer than I have been in the house.

There's a washing machine directly under the kitchen which drains into a basin as well. It drains slowly but otherwise seems to work well.

Who do you think is correct?

How to clear the blockage?

Thanks!

Hello soccref, Im guessing that sense it is an old house that its probably an existing drain problem and with the grease you poured down it finished plugging the drainline.
First don't ever pour grease down your sink drain, that's going to always cause drainage problems sooner or later.
Your need to call a plumber to rooter out your drainlines, its probably been a while sense its been serviced, if ever. Good luck----Zeke

It usually takes some time before drains clog up. I don't thing one cup of grease would cause complete drain blockage. Kitchen drain is the dirtiest drain in the whole house. It is even worse if washing machine is hooked up to the same drain with kitchen sink. I don't think you are at fault.

I share a room in an old house. In the first few weeks I put no more than 1/2 cup of grease in the garbage disposal and chased it with hot water.

The sink has 2 basins. Now when we run water in either one, the water came back up the other - much dirtier than it went down.

The landlord says that my little bit of greased caused this problem. I suspect that the blockage has accumulated over time - a time much longer than I have been in the house.

There's a washing machine directly under the kitchen which drains into a basin as well. It drains slowly but otherwise seems to work well.

Who do you think is correct?

How to clear the blockage?

Thanks!
While it's not the best practice to pour grease down a drain I think your grease was the final straw to a blockage that already existed.
It sounds like the blockage is in the lateral,( horizontal) line in the wall. The solution would be to remove the "J" bend from the trap and send a snake up into the wall,(see image) You will hit a bend about 6' in but once around that you'll have no more then 6 feet of cable to put out. After you replace the trap flush with a tub full of hot water. Good luck, Tom

Well when mine did that I just ran really hot water down it with some liquid plumber and plunged it a few good times and it went away.

well when mine did that i just ran really hot water down it with some liquid plumber and plunged it a few good times and it went away. I don't recommend putting harsh chemicals in your drainage system. If it doesn't remove blockage you are left with a sink full of caustic chemicals that will blind you if you get it in your eyes. Besides they only seem to work in TV commercials. Snaking a drain is the only sure way to remove a clog. Regards, tom

Thanks for all the answers. I see a common thread and asked the landlord to call a plumber.