I live in a cement shoe box in Fla. By the process of elimination I believe the leak coming from under my cabinets, is from the drain pipe. The pipes that are hot and cold are not leaking, the drains under the sink are dry and not leaking, after I drain the sink full of water, the inside cabinet remains dry, but the sink water -bubbles and all comes out from under the wood cabinets, in the low spot . The pipe is cast iron, and I have traced it in the far corner of the cabinet, then it goes down and into the cinder blocks. Were do I start ?

By calling in a plumber. Cast iron pipes are not easily replaired or replaced by a DIYer especially incased in cement. They may be able to reline the drain so call around and find a plumber or contractor who can do relining, much cheaper than replacing. Tom, aka Speedball1, lives in Florida and may have more info for you in the AM.

Thanks so much.