Dissolve 3/4 cup sugar in 2 litres filtered water. Place in large glass jar with kefir water grains. Cover with cheesecloth or similar, rubberbanded in place. Set on the bench and ferment for 3 days.
Strain kefir through a sieve, catching the grains to start the next batch. Bottle the liquid into glass bottles, cap, and ferment for a further 3 days at room temp. Transfer to fridge and enjoy.
Over time, the grains will multiply - when you have too many, then discard some, or put into a container with some liquid to cover, and distribute to friends so they can start their own kefir ferments!
Note: like all ferments, this can get quite fizzy, and the old overflow/explosive bottle is possible. So don't keep it in your linen closet! A chilli bin is a great, contained place to put bottles for the second ferment, whether for kefier, kombucha, or similar.