This hike is a one-way hike which means that you have to go back the same route as you came. However you will see that there are several junctions that allow you to walk slightly other routes on your way back. Some are longer than others. We chose to only take a small detour and partially walk a different path on our way back. However these routes are not that well marked, so it can be a little more tricky to find your way. We usually use an App called Maps.me while hiking. It allows you to download the map of an area and can locate you even without having internet access. Also hiking trails are marked way more in detail on Maps.me than for instance on Google Maps, which makes it convenient for hiking.
The one way hike to the 25 Fontes waterfall is around 4,3km (8,7km round-trip). The detour to the Risco waterfall around 1km one way. Our route was a little longer since we chose to take a small detour at the end.
You can download a brochure with the official route on the official tourism website of Madeira. The detour routes are not marked here but you can find them on the Maps.me map.