One of the features which the Volkswagen Beetle has retained since 1962 is the windshield washer system. Though it has varied in some details, it has remained a pressure operated system. The fluid bottle was to be filled with clear water or a windshield washing fluid which could consist of an anti-freezing-cleaning solution for winter months or for colder climate zones.
This bottle was also marked with either a yellow or red decal. Both are correct. It just depended on what the factory had on hand.
Pressure in 1961 was generated by a diaphragm—the switch was pulled to activate a diaphragm which pulled water from the unpressurized fluid bottle and pushed it through the washer nozzles onto the windshield.
For 1962, the bottle was changed so that it could be filled with liquid, the cap screwed shut and the bottle pressurized by use of a tire pump or some other source of compressed air. The washer hose, of course, changed to accept this pressure. The hose was routed around the gas tank to the passenger’s side and then to the washer switch. The bottle cap (in the Owner’s Manual illustration) was white and knurled.
Helphos was a major manufacturer of the washer bottle (perhaps the sole manufacturer). In the photo below, Logo and other identifying information has been highlighted in black for illustrative purposes only.