At our booth at the Sweet Potato Festival the young firefighters from Aljezur’s body came along to inform about their activities. In the conversation we came quickly to the curious subject of biological pools, because of course, it totally attracted the little firemen’s attention. We informed about functions, sizes and even prices. What made them even more enthusiastic was the fact that swimming pond do not only provide a reasonable water supply, comparable to a fire-fighting pond, but that they are all equipped with a fire service connection (SI). They said this is, in fact, is well done. The biological swimming pool installed for bathing has yet another important functionality and safety aid! Finally we calculated together the equivalent of the content in numbers of firemen’s tankers that fit in a biological pool.