It appears there might be a misunderstanding regarding the location. “Mariehem” is not a recognized or verifiable place name in Portugal according to available geographical data.

As a travel expert committed to providing only real, verifiable data, I cannot offer specific information about free water fountains in a location that does not exist. Providing details for a non-existent place would involve fabricating information, which directly violates the critical instruction to “Never make up statistics, prices, or facts.”

If you can provide the correct name of the city or region in Portugal you are interested in, I would be happy to provide accurate and verifiable information about water fountain availability, typical locations, and general tips for finding and using them, as well as mentioning tools like AllInMap.