How much you add is really up to you.
But to start, there are 20 drops of water in 1 ml.
The Drave Water Pipette is designed to be a 1 ml measure of water when taken from the submerged triangular facets.
A recommended pour in the Norlan Whisky Glass is 20 to 40 ml.
To dilute a dram by 10% in the Norlan Whisky Glass, take two drops from the pipette for a 20 ml pour or four drops for a 40 ml pour.