Hi. Sorry for a late reply, but I was out of station.
Regarding the roads to Kanva reservoir, its a straight route to Ramnagaram on Mysore Road. After Ramnagaram there is a Kamat Lokaruchi hotel on the right side. Around 1 km after that there is an arch on the right through which an 8 km long dirt track takes you to Kanva. That dirt track can be an irritant in rainy weather.
From Kanva you can go to Savandurga without returning to Mysore Road. There is an internal route through scenic countryside which is fine for the most part with some potholes at selected stretches. For this you can ask the locals the route or you could ask xbhp member dj666, he talked to the locals on the way. I don't know Kannada otherwise I could have an idea of it.
Hope that helps
