I have a small drip leak (maybe one drop every 5 seconds... ) in a cast-iron drain pipe from my bathroom. Is there a fix that would last about a year that would not involve a plumber? I am planning a renovation on the bathroom, but need to keep it functioning in the meantime. Any suggestions would be greatly appreciated.

We can probably get you through a year but need to know exactly where that drip is. Which pipe and where is it located in the bath, under the sink?

The drip is coming from a spot where two pieces of the pipe are joined, along a horizontal segment of the drain from the bathroom. I just happened to notice this after flushing the toilet. :( Luckily, it was only water :)

Thank you!

OK it is starting to sound like this may be the drain from the sink. Please clarify which fixture this drain is connected to since the drain I picture has nothing to do with the toilet.

It is a 4-inch cast-iron waste pipe from an attic bathroom. Both the toilet and the sink lead to this drain pipe. Since the pipe is completely horizontal (doesn't have an angle as it should... ), the leak starts about 10-15 seconds after flushing the toilet. My guess is that it is coming from the residual water remaining in the pipe.

Cast iron is sealed with oakum and hot lead but the good news is that there is no real pressure in this pipe like a supply line. If this is just tempoary you can patch it to tide you over but don't let this become a permanent fix. Don't use this toilet for awhile to allow the drain to dry out. Wipe down the area around the connection with alcohol or laquer thinner and allow to evaporate. Caulk all the way around the connection with silicone sealer making sure to get good contact on both pipes. Allow to air dry for a day before using the toilet, hope you have a back up toilet.

Thank you for your help. I will try this suggestion. Do you have any suggestions for a particular type/brand of caulk?

The best pure silcone you can buy, maybe GE silicon but remember this is a temporary fix, jury rigged, not permanent. You might also add some support under that joint, it may have a slight sage and that's what opened the lead.