Fontavio shows where water is along a hike, so you can see what is ahead and plan what to carry.
Fontavio maps drinking water, natural springs where their potability is documented, and the toilets, showers and laundry at the places you stop. Seasonal closures are shown where known.
With Pro you can download the area you pick, base map included, so the map works without signal.
One caution about natural water sources: a spring is only shown as drinking water when the source data says it is safe. When potability is contradicted or unknown, it is mapped as raw water instead. Treat unverified water accordingly.