The water shower is optional. The important part of this is the firefighter on the right of the picture who operates the bellows to provide fresh air for the one wearing the mask.
The König’s helmet was very successful with about 6000 units sold and his company still fire fighting equipment and uses that helmet in the company logo.
[Info and description courtesy of /u/Sigeberht of Reddit]
I find it hard to believe since I saw the exact same helmet in a museum in germany where there was an exhibit of “failed inventions”
Apparently the version without the head sprinkler is the one that was most widely adopted.