The main objective of this paper is to propose an alternative for the stormwater management in low-income communities, settled in urban vertical slums, located in areas with insufficient infrastructure and degraded environment. A case study located in Rio de Janeiro City, Brazil, is presented. The high slopes of the studied area are used to favor the superficial flows, generating alternatives for the traditional stormdrains used to collect the runoff of the upstream reaches. A small reservoir is proposed for each house, reducing flood volumes by allowing rainwater harvesting, and a greater retention reservoir is introduced as a storage measure for connecting the microdrainage coming from the informal city to the formal city. The different scenarios were simulated with the aid of a mathematical model called MODCEL and the results showed that it is possible to apply an effective drainage system solution in informal areas, without affecting the already implemented downstream formal drainage network. The retention reservoir proposed also introduces the possibility to act in improving the water quality to downstream areas, although this complementary aspect is not developed in this study.