Above, someone mentioned rebar in the foundation. That is a Ufer Ground. In places with very dry soil you can pound a stack of ground rods into the earth and still not get a good ground. Ufer figured out that concrete in the foundation provides a good ground.

https://en.wikipedia.org/wiki/Ufer_ground

5 years ago I built my house and did my all my electrical, I needed a Ufer ground in the foundation and 2 ground rods near the meter. Being a newer area, water lines were plastic.