The main theme in this thesis is potentials for increased user participation in the development of ecological sanitation technologies. The argument is that ecological sanitary engineering can be regarded as a heterogeneous practice that needs to incorporate environmental considerations as well as users’ knowledges and aspirations. To be a heterogeneous engineer therefore means to acquire skills for advanced dialogue with the users and other stakeholders, rather than providing finished technical solutions. In a case study in rural South Africa, I found that much of the responsibility for taking initiatives for the transformation of the water supply and sanitation systems lies with the community. By contrast, a case study of ecological sanitation in urban Sweden revealed that there was generally very little room for user involvement; instead, sanitation specialists presented a picture of the users as recipients of technical systems and information. These two different cases form the basis for a discussion about the relationship between users and specialists and pose the question of how we can encourage participatory technology development practices that users, specialists and ecosystems can endure. On the basis of feminist theory, technoscience and participatory methodologies, I have identified some criteria for feminist sanitary engineering. These include recognition of diversity, feminism beyond gender/deep feminism, reflectivity and heterogeneous engineering, and action research and user participation. The transformation of sanitary engineering towards the inclusion of these criteria is a long-term process, which needs to begin with reflection among sanitation specialists. / Temat i avhandlingen är möjligheten till ökad brukardeltagande i utvecklingen av ekologiska avloppsalternativ. Två studier ligger till grund; en i Sydafrika, där det lokala samhället har stort ansvar för vatten och avlopp, och en i Sverige, där ingenjörer inom kommunen har ansvar för systemen. Några kriterier för en utveckling av feministisk VA-teknik har identifierats, nämligen erkännande av mångfald, feminism bortom könstänkande, reflektivitet och heterogen ingenjörskonst, aktionsforskning och brukardeltagande.