The ornamental design for a domesticsoda-water preparing device, as shown and described.
1. Domestic soda-water preparing device
1.1: Perspective
1.2: Front
1.3: Back
1.4: Right
1.5: Left
1.6: Top
1.7: Bottom
The shadings in the reproductions represent contours only and do not illustrate an ornamentation or decoration on the surface of the product; the parts shown by means of broken lines in the reproductions are not part of the claimed design.