La tarifa de aguas pluviales vinculada a la retención en Poznań — El esquema de descuento por coste evitado de Aquanet (Polonia)

Coste indicativo

Bajo (< 50 000 €) — Municipal small-retention grant budget: 1,000,000 PLN/year, covering up to 80% of device costs (capped at 50,000 PLN for housing cooperatives, 6,000 PLN for individual households).

Tiempo hasta resultados

Largo (> 3 años) — Discount tariff operating since around 2021; current rates effective August 2025.

Personal y competencias

Aquanet S.A. (water utility, administers the tariff), City of Poznań (co-runs the small-retention grant programme)

Condiciones para el éxito

• Property owners installing qualifying on-site retention devices (rain gardens, retention tanks) to reach the >20% retention threshold
• Sustained municipal grant budget to offset installation costs and encourage uptake
• Public acceptance of stormwater charges — a peer-reviewed comparison notes Warsaw and Kraków have not adopted equivalent fees, citing public resistance

Modos de fallo comunes

• No published data exists on total impervious area affected or aggregate retention volume achieved city-wide, so measured effectiveness is unverified
• Public resistance to new stormwater charges has stopped larger Polish cities (Warsaw, Kraków) from adopting equivalent schemes