Which part of Bedok Reservior?
If you're referring to Bedok Reservior (East side, those blks
7xx), then take 22 to Serangoon and then take the MRT for one stop
to Kovan.
If you're referring to Bedok Reservior (West side, those blks
6xx as well as Kaki Bukit), then take 87 to Hougang Int and then
take the MRT for one stop to Kovan. Alternatively, you can take 87
to the Blk 106 that bus stop and change to 115.
Next time please search for the directions thread (a.k.a. Route
Planner thread) and post there. Don't open a new thread.
Thanks.