Unlocking private investment in managed aquifer recharge: Lessons in policy and crisis-driven adoption from Langhorne Creek, South Australia

Managed Aquifer Recharge (MAR) is increasingly promoted as a flexible and climate-resilient alternative compliment to surface storage, desalination, and demand management. However, despite its technical maturity, private-sector investment in MAR for agriculture has remained limited internationally. This study seeks to address under what conditions does private investment in agricultural MAR emerge, and why can it subsequently decline even where water security pressures persist? To address this question, a Political, Economic, Social, Technological, Legal, and Environmental (PESTLE) analytical framework was applied to examine the drivers of MAR adoption and disinvestment, using the Langhorne Creek viticultural region of South Australia as a longitudinal case study. The region experienced two major water crises over recent decades, leading first to private, community-led adoption of MAR to manage groundwater salinity and supply risk, and later to a shift away from MAR following publicly subsidised investment in long-distance surface water infrastructure. The analysis shows that early private investment in MAR was enabled by a combination of suitable hydrogeology, relatively low-cost and technically simple recharge systems, high-value viticulture, social acceptance, community self-organisation, and clearly defined legal rights to recover recharged water. In contrast, subsequent public investment in water supply infrastructure altered relative water costs and risk profiles, reducing incentives for continued private MAR investment despite ongoing climate variability and water resource pressures. These findings highlight that MAR adoption is shaped not only by biophysical suitability and climate risk, but also by policy design, infrastructure investment choices, local agency and water stewardship, and water market settings. The results provide broader insights for regions seeking to mobilise private investment in MAR for agriculture as part of climate-resilient water systems, and caution that public responses to water crises can unintentionally undermine locally led, adaptive groundwater solutions. • In Australia there has been limited private sector investment in MAR for agriculture. • A PESTLE analysis assessed the factors MAR investment in Langhorne Creek. • A crisis coupled with suitable hydrogeology, a proactive farmer community, innovative policy favoured adoption. • The results can be used by other regions internationally seeking to promote private adoption of MAR.