Here a 3.5 year Viki uses the bathroom faucet to fill her cup. Note the grip she has on the cup itself: she wraps her long fingers around the cup and only uses her short opposable thumb on the rim of the cup itself. Not a very human-like grasp, where we would swing out thumb out in the opposite direction, but it gets the job done! Clearly Viki also knows how to manipulate the faucet handle to get water as well, though again she does not use a human-like grasp.