Aproveitamento de água pluvial para sanitários em escola pública: estudo de caso no município de Janiópolis - PR

Abstract

The growing urban water stress and the need to optimize public resources drive the adoption of alternative supply sources in educational buildings. This work elaborated the executive project of a Rainwater Harvesting System (RWHS) intended to supply the sanitary fixtures of Block 1 at the Dom Pedro II State School, located in the municipality of Janiópolis, Paraná State, Brazil – an institution operating under a full-time teaching regime. The methodology was based on the historical regional pluviometric survey using data from SIMEPAR and the Instituto Água e Terra (IAT), geometric mapping of the roof catchment area, hydrological demand modeling adjusted to the full-time regime (170 students, 08:00 a.m. to 4:50 p.m. daily), and hydraulic component sizing in accordance with ABNT NBR 15527:2019. Economic feasibility was assessed through analytical cost estimation using the SINAPI-PR reference tables and simple payback calculation. The effective catchment area was set at 400 m², with an average annual rainfall of 1,692 mm, yielding a rainwater supply capable of meeting between 24.23% and 62.00% of the monthly demand during full school months. The designed system comprises a 15,000 L fiberglass cistern at ground level, a 1,000 L upper distribution reservoir, a 400 L first-flush diverter (200 mm parallel column manifold), a 0.5 hp centrifugal pump, and a by-pass complementary feed mechanism. Total implementation cost was estimated at BRL 17,182.80, with annual water savings of BRL 2,316.20, resulting in a simple payback of 7.4 years against a technical service life exceeding 20 years. Beyond the technical and economic dimensions, the work proposed conceptual guidelines for educational actions and didactic signage, transforming the RWHS into an active hydro-environmental laboratory for the school community. The results confirm the full technical and economic feasibility of the proposed solution, reinforcing the strategic role of sustainable civil engineering in the efficient management of public resources.