Just a thought- Could the square shape indicate it may have been one of several in a group- Like it would have been in use in a hotel or restaurant? Does the base look grooved like it would have been fitted to another below it?
I grew up by Alum Rock Park in San Jose, CA which has mineral springs and was a "health spa" of sorts back in the Victorian era, when they used to believe that mineral waters had healthful and curative properties. Even as late as the 1970's when I was riding my horse there, I will never forget a conversation with a very elderly man who kissed the nose of my horse and hugged her. His son had brought him there to collect the mineral water because his father still believed it would cure the ills of old age. I wonder if something like this may have been used for mineral water, although I don't see any signs of deposits I would expect to see with heavily mineral-laden waters. "Curative" waters were big business back in the Victorian era.
Also in San Jose on the southern end of town we also have a "miraculous" spring in what is now the Santa Teresa area. This spring was the water source for the Native Americans living in the area, who had a legend surrounding it that a woman appeared and blessed the spring curing the tribe of an affliction (we now suspect they were sickened by body paint). When the Bernal family took over the lands, being devout Catholics, they attributed the Native legend to Santa Teresa. (They kind of ignored the fact that the legend pre-dated Sta. Teresa by several hundred years!) The Bernals would hold mass at the spring, it had blessings by the Pope and the bottles of miraculous curative water sold like hotcakes... 'specially to the folks that would come to the ranch to watch bull and bear fights! *shudder!*
But to make a long story short, there was a lot of money in health water and I wonder if your filter system was used on a larger scale for an estate, restaurant, spa or ?
