Fuels, inclusive of those produced with the use of wastes, must usually be stored before their combustion or co-combustion in industrial processes. When stored outside, the fuels are exposed to adverse atmospheric impacts. The fuel quality may get worse then and fuel components which may be environmentally harmful may be leached out as well. The paper presents the assessment of potential environmental threads which result from the storage of fuels which have been produced with the use of municipal sewage sludge and other components,