What is the importance of Taiyang Arcology in the novel, The Water Knife?

The Taiyang Arcology is an artificial ecological indoor environment constructed in Phoenix for wealthy residents. The lifestyle of those who live in the Taiyang (known as “fivers” due to their five digit addresses) is contrasted to the lifestyle of ordinary people from Arizona (known as “Zoners”). Whereas those in the Taiyang have air-conditioning and reliable access to water, Zoners are left in scorching and dry conditions outside, forced to rely on charity water pumps and Clearsacs for their access to water.