Tourism brings great opportunities of growth with relatively small investments in physical and human capital, but it also comes with important negative externalities. This paper looks at the environmental cost of tourism in terms of solid waste produced in municipalities. Using the Data Envelopment Analysis developed by Charnes et al. (1978) and Banker et al. (1984), the paper estimates the efficiency of Tuscan municipalities in waste management and relates this measure to spatial and touristic variables. The scale of operations is also considered to see if tourism seasonality has an impact on the ability to operate at optimal scale. The empirical analysis suggests that seasonality has a negative effect on the efficiency of solid waste management and that this effect is primarily due to difficulties in operating at optimal scale. The seasonality of presences has a strongly negative impact on efficiency while tourists’ average stay has a positive effect once scale effects are considered. The implications are that more effort should be made to flexibly manage waste collection in localities affected by seasonal tourism and reduce seasonality by incentivizing visitors to stay longer, for example by introducing a flexible tourist taxation as a function of presences and duration of stay.