Ask Mr. Smarty Plants

Do you mean a Texas Mountain Laurel, Sophora secundiflora (Texas mountain-laurel)? We will assume that is the tree you are considering. We were concerned when we discovered that it is not listed as native to Arizona in our Native Plant Database; however, we then found this article by Master Gardeners on a Pima County Cooperative Extension website, Texas Mountain Laurel. You say you already have one in your yard, so obviously they must be able to live in Arizona.

When you inquire about the roots of this tree attacking your pipes, are you referring to sewer pipes or water lines? The Mountain Laurel has a sparse root system but a deep taproot, an adaptation for survival in desert conditions. Once upon a time, when most sewer lines were clay, like the clay pots,  invasive roots did, indeed, break them up and cause major problems. Nowadays, both water and sewer pipes are more often a heavy-duty plastic material, and don't have as much trouble with roots. The mountain laurel is very difficult to successfully transplant because of that taproot-damaging it in transplanting can be fatal to the tree. We would suggest that you first acquaint yourself with the location of the pipes you are concerned about, including the depth they are in the ground.  You did not say if you intended to plant seeds or purchase a tree for transplanting, but it would be a good insurance policy to not dig the hole for the tree directly over those pipes. The resources we searched made no mention of intrusive roots from this tree, just cautioned about the difficult of transplanting the tap root, as well as warning that the tree grows very, very slowly.

From our Native Plant Image Gallery:

Sophora secundiflora

Sophora secundiflora

Sophora secundiflora

Sophora secundiflora