Preheat oven to 425 degrees. Line 2 rimmed baking sheets with parchment. In a saucepan, bring water, butter,sugar to boil over high.
Immediately remove from heat. With a wooden spoon, stir in flour. Continue to stir until mixture pulls away from sides of pan, about 2 minutes. Let cool 2 minutes.
Add eggs, one at a time, mixing after each addition until batter comes together. Transfer batter to a zip close bag: twist so batter is in one corner. With scissors, snip a 1/2 inch opening in corner (or use a pastry bag with a 1/2 inch plain round tip).
Pipe batter into desired mounds (1 tsp makes about 110, 1 1/2 tsp makes about 60 or 2 tsp will make about 40oval eclairs) 1 inch apart, onto sheets. With a wet finger, smooth out the pointy tops. Bake 10 minutes. Reduce oven temp to 350 degrees and bake until puffs are golden brown and feel light and hollow inside, 20-30 minutes. Let cool on sheet on wire racks.