Holly Springs plumbing is dominated by replacement-cycle work on relatively young housing stock, which makes the buyer mix and revenue mix very different from Garner or even Raleigh. Most homes were built between 2000 and 2015 with PEX or copper supply and PVC drain — you don’t see the polybutylene re-pipe market that drives Cary or the cast-iron drain replacements that dominate ITB Raleigh. What you do see is a steady curve of original 40-gallon and 50-gallon tank water heaters from Wescott, Sunset Ridge, Sunset Oaks, Holly Pointe, Cobblestone, Highland Glen, and the original 12 Oaks villages reaching their 12–18 year failure window simultaneously, and a strong upgrade-to-tankless conversion appetite among the biotech / professional buyer base.
Pool plumbing is a real revenue line in HS, especially around 12 Oaks (the Pulte planned community design encouraged private pools and several sub-villages have community pools driving aspirational private installs) and the Sunset Lake / Sunset Ridge cluster. Pool plumbing service, hot-tub plumbing, irrigation back-flow assembly inspections, and outdoor-kitchen plumbing all run on a spring/summer cycle that most HS plumbing sites don’t explicitly market for. A handful of older pockets in original Holly Glen and along Avent Ferry have legitimate sewer-line work as 1990s clay laterals fail, but the volume is far smaller than in older-stock cities. The dominant buyer in HS is comparison-shopping methodically with a ~$110K household income and treats permits, warranties, and brand-name fixtures (Rinnai, Navien, Rheem, Bradford White, Kohler, Moen) as decision factors.