ChatGPT is the citation engine for plumbing — both Chicago and Houston plumbers are cited there, and neither appears in Google AIO or Perplexity. Atlanta plumbing (38) has good consistency signals but thin citation source coverage, resulting in zero citations. The citation pattern is driven by review volume and aggregator presence, not structured schema.
ChatGPT
ChatGPT is the citation engine for plumbing — not Google AIO or Perplexity
Both Chicago and Houston plumbers are cited in ChatGPT only. This pattern suggests ChatGPT draws more heavily from aggregator sources (HomeAdvisor, Angi, Thumbtack) that plumbing businesses are typically listed on. Plumbing businesses optimizing for Google AIO alone may miss the engine most likely to cite them.
Reviews
Review volume and aggregator presence are the primary citation drivers
The Chicago plumber cited in ChatGPT has 400+ GBP reviews and HomeAdvisor presence. The Houston plumber has similar signals and is cited first in ChatGPT responses. In plumbing, review volume and lead-generation aggregator presence appear to compensate for thin structured schema.
12 pts
Atlanta Plumbing scores 12 points lower than Chicago — and gets zero citations
Atlanta Plumbing (38) vs Chicago Plumbing (49) is a 12-point gap. Atlanta has consistent NAP and BBB accreditation — identity consistency is solid. But it's missing from the aggregator sources ChatGPT draws from for plumbing recommendations. The fix for Atlanta is citation source expansion, not schema optimization.
License
Plumbing license numbers in structured data are a Top-tier differentiator still unused
No plumbing business in this cohort has reached Top tier (58+). The structured signal most commonly absent is license number in LocalBusiness schema. Plumbing is a licensed trade — the license number creates a verifiable credential that AI engines can cross-reference. Businesses adding this signal see improvements in B3 (NAP Consistency) and B5 (Entity Recognition) components.