Alternative Residential Wastewater Management in Coastal South Carolina: A Discrete Choice Experiment Approach

Residents’ valuations of improved wastewater management options provide critical insights for policymakers seeking to design effective residential wastewater strategies. This study focuses on coastal residents in South Carolina who rely on onsite wastewater treatment systems (OWTS) to quantify their valuations of alternative treatment options — such as regularly maintaining OWTS or connecting to centralized wastewater treatment systems (CWTS) — and identify behavioral barriers that constrain these choices. Using a Discrete Choice Experiment, we find that residents view wastewater management as a collective responsibility, placing significant value on alternative treatment options when social uncertainties (i.e., risks of others’ mismanagement) are reduced through mandated OWTS maintenance. Across both voluntary and mandatory policy settings, residents strongly oppose long delays (over one week) in receiving septic services, as such require a compensation of about USD 77–140 per month for such long waits. Under the mandatory policy, residents are also willing to pay approximately USD 24–28 per month for a 10% improvement in stream and estuarine water quality, whereas under the voluntary policy they are unlikely to do so due to social uncertainty. Welfare analyses suggest that improving septic service provision — such as reducing long delays — could generate substantially larger societal welfare gains than policies that rely primarily on environmental messaging to encourage water quality improvements, regardless of whether septic management is voluntary or mandatory.