We’ve built multiple flex projects on septic, and done right—with the right expectations—it can absolutely work. A few tips from experience: - Start with the installer, not the engineer. A good local septic installer can usually give you a tremendous amount of practical design input for free and potentially save you thousands before you ever engage the engineer. - Demand drives system size, and users drive demand. When you do bring in the engineer, make sure you both agree on realistic daily volumes based on the actual tenant mix—not just a generic commercial assumption. - Large system vs. multiple smaller systems? It depends. Personally, I tend to like multiple smaller systems, but soil, site layout, phasing, setbacks, and local requirements all matter. Again, start with the installer. - Know your bad uses upfront. Hair salons/barbers, food uses, RV-related wastewater, breweries/alcohol production, and other high-water or high-strength wastewater users can make septic impractical or unaffordable very quickly. For traditional light flex users, septic has not been a deal breaker for us. The key is designing for the users you actually intend to have and controlling the uses that can overwhelm the system.