The article discusses the role and methods of rainwater management in a modern city. Cities are currently facing the challenge of adapting to climate changes that are occurring more and more frequently and in an increasingly violent form. The work takes into account urban concepts that emphasize the balance between built-up areas and biologically active areas, building solutions to make cities more resistant to the effects of climate change, due to the relationships between rainwater management, built-up areas and biologically active areas. The issue was presented in the context of the legislative conditions applicable in Poland in the field of spatial planning, as well as the importance of water in the ecological and aesthetic context in urbanized areas. The research was conducted using Scalgo Live solutions. The aim of the paper is to present comparative studies of three variants of rainwater management on the example of a selected local spatial development plan. The presented study focuses on the issues of rainwater management and their direct impact on the size of biologically active areas, with particular attention paid to the potential for introducing modern pro-ecological solutions on an urban scale.