This is a great loop. There’s good parking at the water treatment plant in Ossining which puts you right on the aqueduct. A quick right hand turn, one killer hill, then through Teatown, more killer rolling hills, then the Croton dam, then a final three miles on the aqueduct back to the car.
You can even stop in Teatown and use the bathroom, get water, and buy gifts at the gift shop. OK, maybe no gifts.
But all in all, a great loop to be sure.