Wow! That's really airing your dirty laundry in public, I can imagine how scandalised everyone must have been. What a find.
A "Hydro" is a term everyone here in Scotland is probably aware of, there were several Hydropathics around the country. Crieff Hydro and Dunblane Hydro are two which are still going strong. There was one at Seamill and another up north, Strathpeffer I think.
The one at Crieff (I was there to meet an elderly cousin a few weeks ago) used to be a "Temperance Hotel", which meant that it did not sell alcohol of any kind, not sure if it was the same rule for all the others but I wouldn't be surprised. It was the Victorian "healthy body - healthy mind idea.