The Vaucluse town of Pernes-les-Fontaines is known for its fountains, many of them 18th century and some of them declared National Historical Monuments. The town's tourist office has a map available online that lists 40 fountains and lavoirs, with a route map if you want to explore some or all of them.
Available online from the Pernes-les-Fontaines Office de Tourisme is a PDF document with a map of the fountains and lavoirs, and a couple of routes you can follow to visit them.
Our method was to tour the old town as thoroughly as we could, wandering up and down all the little streets, and discovering the fountains, along with the many other old things to see in the Medieval center. Since the fountains are pretty much everywhere, this is as good a method as any, unless you really want to see them all systematically. You could, of course, mark out the few you really don't want to miss, then just wander and see if they show up; then seek out the ones you missed.
Fountain season is April to June. Water is turned on for the fountains at the beginning of April, so the best time to see them is in these early months. During the high summer months of July and August, fountains could possibly be turned off to conserve water at the requirement of the regional authorities, if it's considered a drought period (sécheresse).
Town Water versus Source Water. Many villages in Provence use natural source water for their fountains, from local springs or streams. French laws stipulate that fountains or lavoirs fed by a natural source must be analyzed for health safety reasons every 15 days. The analysis is done by private companies at normal commercial rates (which are not cheap). For a town like Pernes-les-Fontaines with 40 fountains to test every couple of weeks, the cost would be excessive.
The solution taken here, and in many other towns and villages, is to use city water (eau de ville) for the fountains. This water is continually tested already, and so only costs the normal water rates. This is still pricey, so the water to the fountains is typically cut off during the winter, to reduce costs and to prevent to possibility of freezing pipes during a cold winter.
This is the mossy Fountain Villeneuve, at the Porte Villeneuve at the west side of town. The green moss covering goes brown during the winter months, but will grow back nicely in the summer.
A rather sad transformation in the last few years is the Fountain du Cours de la République, at the far eastern edge of the old town. Once enshrouded with a centuries old covering of calcaire stone buildup and covered in moss, this fountain is now (2017) stripped down to its naked origins. We find it much less picturesque in its "birthday suit" configuration.
Since we took most of our more recent photos at the end of winter, before the water was turned on, the Office de Tourisme of Pernes-les-Fontaines offered us a few photos with sun and water. This is one of them, of the ancient stone fountain on Rue Victor Hugo. Note the photo is copyrighted by photographer J. Paturel.