Which of the following is a long-term consideration for septic systems?

Future expansion of the site is a long-term consideration for septic systems because it directly impacts the design, capacity, and placement of the septic system. When planning for a septic system, it is essential to consider how the property may be developed in the future. This includes the potential for additional structures, which may increase the load on the septic system and require adjustments in size or type of system installed. A system must not only meet current needs but also accommodate any planned expansions to ensure that it remains effective and compliant with local regulations over time.

The other options may not significantly influence the long-term viability of a septic system. Changing decorative trends are aesthetic and do not impact the functionality or design of the system. Height of nearby buildings might affect certain environmental factors or permits but does not directly pertain to the operational aspects of the septic system itself. Variations in soil color might indicate changes in soil composition or drainage but are not a primary long-term planning consideration as compared to future site development.