I prefer to run without having to wait for the traffic lights so a big bulk of my training for the upcoming Standard Chartered Half Marathon is done at Bedok Reservoir.
There are 2 main running routes, the 4.3KM packed gravel loop around the reservoir and the 2KM paved path that begins beyond the car park.
I usually run on the 2KM path because it is paved (no gravel accidentally getting into my shoes), cooling as most of the path is shaded by tall trees, have some elevation, a toilet at the 250m mark, and a water cooler and toilet at the 1KM mark. The distance covered is also almost the same as the reservoir loop when I run to and fro (4.3KM VS 4KM).
I have yet to stop at the 1KM marker where the water cooler is, but I think the availability of a water cooler in the middle of the 2KM path is great since you can now do a long slow run here and not carry water with you. I have this water cooler problem at East Coast Park as there is only 1 water cooler on whole long stretch of the park so I have to hold a small bottle of water while running which spoils my running form.
The reservoir is easily accessed as there is a bus stop (Bus no. 5, 18, 21, 22, 28, 59, 65, 66, 67, 69, 168, 228) right outside the reservoir and there are 2 Electronic Parking System (EPS) enabled car parks (no longer free parking) at the reservoir.
I hope you will enjoy Bedok Reservoir for your runs as much as I do!