"с тех пор" word-by-word means "from those times"
"до сих пор" = "up to these times"
Technically they are not idioms but set phrases because they are used in literal sense.
"с тех пор до сих пор" is understandable but a bit funny because it sounds like tautology.
"С тех пор много воды утекло" yes, this phrase is quite common.