Be sure that you have examined the tap first. Click on the items that will determine that electricity can be made.
Then also talk to the zombie also to know that he needs electricity to finish his projects.
Then verify that you made the homemade water wheel correctly

Check the electric cables by the water tap.
Look at the wooden boards and electric cables at right side of work table.
Look at large machine at bottom right. Look at junk-refrigerator door at left.