When I was training for a marathon back in 2012, I started mapping all the water fountains and bathrooms I came across in the Orlando area. I live in Baldwin Park and my long runs would take me about 6-8 miles away from where I live. Even though I carried a water bottle, for runs that lasted up to 4 hours, I eventually ran out after the first 1-2 hours, especially on a hot day.
Using Google Maps, I pinpointed each water fountain and bathroom. I couldn't find a way to use a marker to distinguish the water fountains and bathrooms, but you can use the legend on the version on the Google Maps website to scroll through and find where I noted a bathroom.