I have a peculiar problem. All of the plumbing fixtures on one side of my house have been noticeably sinking (shower head, sink faucets, bathtub spout, etc.). The strange part is that there are no visible signs that there is a foundation problem like cracks in the slab, drywall cracks, exterior brick/mortar cracks, etc. I had a foundation engineer out to my house last year for a different problem and he didn't detect anything. I had a plumber out a couple of months ago and we looked inside the wall at the plumbing and none of the pipes were loose. He said he thought it was a foundation problem. There are several red-tip photinia bushes that are about 10 feet tall next to that side of the house - could the roots be wrapped around the pipes and pulling them down? Any other ideas? Thanks!