drip in(to) (something)
1. To slowly trickle into something, as of a liquid. There must be something wrong with the faucet because water is still dripping into the sink.
2. To slowly trickle something into something. Just drip the food coloring into the cake batter so that you don't add too much of it.
drip in
(to something ) [for a liquid] to fall into something drop by drop. The water dripped into the bowl we had put under the leak. Is the water still dripping in the bathtub?
drip something into something
and drip something into make something fall into something drop by drop. Alice dripped a little candle wax into the base of the candlestick. Don't pour it all into the jar. Drip in a little at a time.