I get criticized regularly about drainage and grading issues I include as Action (repair) Items. Until about the year 2000, drainage and grading was a complete afterthought by builders that resulted in many class action as well as individual home owner and HOA law suits. Engineered drainage and post tension foundation slabs have finally eliminated these issues for most new builds after 2000. Up to about the late 1960’s, many Phoenix homes used and many still use “flood irrigation”. The lot is bermed at the perimeter and sloped away from the building to create miniature lakes on the property after X number of gallons are pumped onto the lot. This allowed people to have grass that doesn’t belong in the desert in the first place. It was the worst of bad ideas. This brings me to the top two reasons why drainage and grading is really important. We have Subterranean Termites that are attracted to moisture so flood irrigation, planting vegetation requiring watering within 3′ of the building and unchecked vine growth on building walls are all major no no’s. Most homes built between the late 70’s and the year 2000 included “floating” concrete floor slabs. Over the years I have reported on hundreds of major issues with floating floors. Every last one of them caused by negative drainage to the building walls, overwatering vegetation against the building, undetected broken sprinkler lines etc. Many issues were caused by the homeowners ill advised landscaping dreams that created unintended consequences.We also have pockets of “expansive soils” in Maricopa County that are like a sponge that grows larger when wet and have caused major structural issues when left unchecked. If you search “expansive soils Maricopa county” you will find more information than I can provide here. The USGS site will have the most up to date info.