Professional plumbers should be familiar with the information contained herein, so this post is really aimed at the non-professional. Toxic waste dumping by drug (meth) lab activities eventually results in breached drain pipes. If such a breach occurs in a wall, leaking moisture within the wall will result in the growth of mold and mildew there, no small problem. Such dumping can also result in the breaching of a sewerage connector pipe which is very frequently imbedded in the slab of a structure. It seems that the incredible growth of mildew caused by such a breach is not killed by the toxins that are being dumped; to the contrary, mildew seems to feed on such toxins. Now, here's the really big thing: if the abuse of drain pipes is severe enough, the sewer line out in the middle of the street can be breached. Just such long-term abuse and damage to the city sewer line occurred in a Bronx, NY case a number of years ago on a residential side-street. Because the ground below the street was being eroded away by liquid flowing out of the breach in the sewer line, a huge depression formed in the middle of the street. The City of New York addressed the situation by paving over and filling in the depression a number of times. Eventually, city engineers sent a camera down the sewer line and determined the existence of the breach WHICH, IF LEFT UNADDRESSED, COULD HAVE RESULTED IN A GIGANTIC SINKHOLE DEVELOPING AND SWALLOWING CARS AND THE SCHOOL BUSES THAT PASSED ALONG THAT STREET! Eventually, the street was opened up, and the sewer line was repaired. You would not believe the extent of that undertaking which must have been very, very expensive (maybe on the order of $1,000,000+). No arrests were made in the case, and maybe by now, many years later, repairs at the same location must be done yet again. I refer you to my replies #24 and#25 at thread entitled, "Paint smell in bathroom after showering" in the painting forum. Twice, for your convenience, I attempted to include the link to my post, but, sadly it just wasn't working, so I just decided to eliminate links here all together. Perhaps the best way to access my replies #24 and #25 in the other thread is to click on my screen name to the left, then click on "Find more posts by labb_sleuth." Thank you L.B.