This paper examines methods and strategies for addressing environmental stewardship within the humanitarian aid water and sanitation sector with a focus on case studies from the 2004 tsunami recovery effort in Indonesia, Sri Lanka, and Maldives. During the recovery phase following a natural or technological disaster, humanitarian aid organizations are uniquely positioned to implement water and sanitation activities that go beyond disaster recovery to provide beneficiaries with water and sanitation systems that are more environmentally sustainable than pre-disaster conditions. Oftentimes, however, the pressure to rapidly restore post-disaster water and sanitation systems leads to a lack of coordinated planning and missed opportunities to implement innovative technologies that can make communities more resilient to future disasters and reduce long-term ecosystem impacts. Following the 2004 Indian Ocean tsunami, several humanitarian aid agencies recognized the importance of integrating environmental sustainability concepts into their water and sanitation relief operations. Methods for addressing environmental sustainability included co-locating environmental specialist staff within field operations, constructing pilot projects of environmentally beneficial small-scale technologies, integrating watershed planning with humanitarian aid, and participating in multi-stakeholder water and sanitation working groups. Challenges to the institutionalization of environmental stewardship concepts in humanitarian aid operations include overcoming the perception that environmental stewardship will always be more time and resource intensive than conventional alternatives, establishing organization-wide policies that are enforced at the field level, actively promoting intra- and inter-organizational learning, and providing readily accessible, practical field tools and training for aid staff. Lessons learned from the application of environmental stewardship approaches in the Indian Ocean tsunami response can be applied to future humanitarian aid relief operations.