For the syrup, combine water with sugar and bring to a boil.
Pack jars with washed plums. Pour syrup into jars. Clean tops of cans. Close lids, screw the rings on just enough for them to seal but don’t screw too hard as air bubbles may need to escape during cooking.
Cook plums for 15 minutes.
Remove from water and tighten rings on jars. Place towel on countertop or table. Flip jars over. Cover with another towel. Leave overnight.
You can either discard of the plums or add them as well. If you don't want any little plum pieces, run the kompot through a sieve.