On a long ride, water runs out faster than food and matters more. The trick is not carrying more, it is knowing where the next reliable source is before your bottles are empty. I have refilled from cemetery taps at 2am and rolled into towns bone dry more than once; here is where to look, and how to know in advance.
Public fountains. Common in Italy, France, Switzerland and much of southern Europe. Free, drinkable, and often marked on maps. In some regions you can plan almost entirely around them.
Cemetery and graveyard taps. The long-distance rider's secret. Almost every cemetery has a tap for watering plants, drinkable in most of Europe, and open when everything else is shut. Invaluable at night and on Sundays.
Fuel stations. Reliable, often 24/7, with bottled water and a tap. Your safety net when nothing else is open.
Cafes, bars and restaurants. Ask to refill; most will oblige, especially if you buy a coffee. Bars in Italy and Spain are used to it.
Churches, sports fields, campsites and public toilets. Frequently have an outside tap. Campsites will usually let a passing rider top up.
Natural sources (streams, springs). A backup in remote terrain, but treat or filter unless you know it is safe. Never your primary plan near farmland or towns.
Guessing is what gets you in trouble at kilometre 300. Public tap and fountain locations are in open data such as OpenStreetMap, but scattered across a map and not tied to your route. The useful version is seeing every source along your exact line, with how far it sits off route, so you know your longest dry stretch before you start.
That is what Rekker does: drop in your GPX and it lists the drinking water along your route, cemetery taps included, so empty bottles stop being a navigation problem. Water is always free in Rekker.
Once you know the gaps, size your bottles to the longest one, not the whole day. Our water and food carry calculator turns your longest dry stretch, speed and the heat into a rough litre target. And remember that opening hours matter too: a shop full of drinks is no use if it is shut, which is where our guide to opening hours across Europe comes in.
Map the water on your route, freeDrop in your GPX and see every tap and fountain along your line, offline on your phone.