There are a few topics/threads on the subject of using a shower installation for enemas or douches. I think I've written cautionary notes in at least two of them.
One of my comments would only concern, as far as I'm aware, the UK, and that is the matter of additives such as chlorine (in ever increasing quantities these days because of the age of the infrastructure) and the compulsory medication we get in the UK by means of fluoride (a poison by any other name) added to preserve the dental health of children who cannot be bothered with, or are not taught, oral hygiene.
Those are just two of the reasons I would not use towns (municipal) water in my gut.
Many of our members talk about toting their enema apparatus around with them to hotels, on business and on vacation - even on cruise liners. Of course not all will hook up their shower equipment, though some might, but they will no doubt mostly use the 'house' water in bags etc.
Now, hotels, particularly tall buildings, will have their water supplies, for hot and cold, housed in rooftop/penthouse tanks. No doubt there is a cleansing programme in place. Equally without doubt is the plain fact that sheer economics will ensure this is done but scarcely, if at all.
Now, having regard to the things I have found in storage tanks of this nature in my days as a building services engineeer, things such as the janitors used condoms, dead rats etc - nothing of that nature and from that type of source is going to be ingested by me, at either end of my body.. I'm not going to even bother to detail about cruise ships, save that the rats will be foreign ones!
So, what do I drink or inject into my rectum in a hotel? Bottled water of course - but check the analysis on the bottle because minerals are always present there. And cruise ships? Not my idea of fun!