Scaling Resilience from the Home to the Basin: Water Resilience Lessons from the Indonesian Bak Mandi
Sometimes, you can find a big idea in small places. In Indonesian households, the bak mandi — a special “extra” water basin in the bathroom — serves a role far greater than its simple form suggests. This everyday domestic solution embodies three key principles of storage, buffering, and cultural resilience that can inform large-scale ecological resilience strategies, particularly in river basin management. Indeed, you can find these principles at large scale in programs such as the Netherlands’ Room for the River. Water resilience at any scale is facilitated by decentralized, adaptive buffering systems.
When searching for a definition online, the “bak mandi’ is often mistranslated as a bathtub, a critical error that misses its true function. In essence, the bak mandi is a traditional water reservoir of about 100 liters designed for daily hygiene and household use. It enables users to bucket out water for washing, tooth-brushing, toilet use, and cleaning without depending on real-time, on-demand, or tapped water supply. This traditional household strategy for managing water availability in Indonesia becomes indispensable when (or where) water delivery proves unreliable. By bridging temporary water supply from the larger water delivery system, the bak mandi reduces vulnerability during outages or scarcity periods.
A subtle importance arises from its daily non-emergency use since the bak mandi requires active engagement: it must be kept clean, refilled, and managed daily. This continuous interaction reinforces water's value within the household and cultivates stewardship habits. Its efficiency also offers environmental benefits: bucket washing uses about 75 percent less water than a conventional shower, while rinsing mitigates the need for toilet paper (along with its associated water footprints and supply chain impacts). The bak mandi thus functions both as a utilitarian device and a cultural practice rooted in adaptive living.
This low-tech resilience model offers an instructive analogy for how we design and manage water systems more broadly. When integrated into piped networks, as is taking place in present house building, the bak mandi becomes part of a hybrid water system—where redundancy and flexibility improve overall reliability. Rather than designing for networks that must always function flawlessly, resilience thinking embraces partial failure, buffering, and fallback mechanisms. In the same way, river systems can be made more resilient by expanding their capacity to buffer floods and store water during scarcity.
Dams and reservoirs often dominate water system design and problem solutions, but the wetlands, lakes, side channels, and floodplains are frequently undervalued or degraded as traditional or less effective solutions. Yet, in complement to purely engineered designs, these natural buffers also perform critical functions: absorbing peak flows, recharging groundwater, and extending the temporal availability of water downstream.
In Europe, the Netherlands pioneered the "Room for the River" program (2006–2018) to accommodate rising river levels under climate change at the cost of 2.3 billion Euro. By moving dikes and restoring the ecological function of floodplains, the program increased discharge capacity by 7 percent, while reducing flood risks and preserving and reconnecting wetlands to the river channel. Recently, however, drought risks have intensified, so the country is now launching Room for the River 2.0, aimed at enhancing water retention and storage. This includes reintroducing side channels and percolation basins, essentially treating the landscape itself as a distributed storage system. Indonesians might call this a catchment-scale bak mandi.
In South Africa in 2022, AGWA worked on CRIDA assessments that defined ecohydrological indicators for risk and resilience for several massive biosphere reserves. Our work highlighted two areas in particular: the flow regime (using a relatively new approach called functional flows) and by analyzing hydrological connectivity, which we defined very broadly, not just in terms of upstream-downstream movement. Both analyses revealed natural buffering to identify critical storage functions across the river networks. These assessments visualized how storms move through basins, located storage points (both natural and engineered), and revealed how connectivity responds under stress. We could then relate these qualities to the basic human and environmental water requirements of the biosphere reserves. The analysis demonstrated the possibility of retaining or restoring floodplains, wetlands, and aquifer recharge zones, not just as habitat but as essential natural infrastructure for water resilience.
The parallel between domestic and ecosystem-scale buffering becomes particularly evident when considering scale and connectivity. A single bak mandi will have practical household uses, but where all households have their own bak mandi, this would allow for more flexibility in water delivery shocks and system design at the scale of a village, a neighborhood, even a dense urban center. Similarly, once nature-based interventions in a river systems are coordinated and connected with all water system interventions across a landscape, these buffers have the ability to significantly improve overall systemic resilience. They provide distributed capacity that complements centralized infrastructure, much like the household basin complements piped water system design. Furthermore, they are culturally embedded: the bak mandi survives not because of engineering mandates but because it is a trusted tool that is in daily use. Water storage buffers in river systems, too, thrive when they are embraced by communities as part of land use, conservation, or agricultural practice. In the Netherlands this is happening where communities appreciate the created spaces, which often have evolved into new natural areas in addition to the flood protection they provide.
In conclusion, resilience in water systems, whether for a household or across a river basin, depends on buffering. The Indonesian bak mandi offers a microcosm of principles that scale redundancy, cultural integration, and the value of intermediate storage. Just as the bak mandi supports household resilience through simplicity and foresight, natural buffer areas enhance basin resilience through ecological function and flexibility. Climate adaptation strategies should embrace these principles at all scales. Planning with CRIDA and related tools can help visualize and prioritize such buffers, reinforcing the notion that resilient water systems are not just engineered, they are experienced, and often have resilience already embedded in cultural practices and ecological functions.
Nikolai Sindorf
Delft, The Netherlands