Went looking for distilled water - everybody out of stock. At Target found their "good and gather" brand "processed by advanced filtration and reverse osmosis technologies" Got some. Removed all the water I could from the reservoir and poured in a gallon. boiler level still fills so reservoir level is ok. Works. Emptied a couple cups out of the hot water spigot and boiler refilled, so there are apparently still enough minerals to allow the reservoir-full indicator to work. I have added no minerals (ie sodium bicarb) edit just added 0.4g sodium bicarb.

Or did I get boondoggled?

kris772 wrote:so there are apparently still enough minerals to allow the reservoir-full indicator to work.

That was probably the case here. It depends on the controller and the sensor but most of them work ok with even a tiny amount of mineral. On some machines, if you use too-pure water it will overfill the boiler. On yours, which I think has a reservoir sensor as well as min and max boiler level sensors I think the most likely effect of too-pure water would be that the controller shuts off the pump and heater, and blinks the lights.

kris772 wrote:At Target found their "good and gather" brand "processed by advanced filtration and reverse osmosis technologies"

It doesn't say "with minerals added" so I think it's reliably pure, and a good stand-in for distilled in a water recipe. There are FDA regulations about what can be labelled "purified drinking water" that have you covered.

Down the road you might want to look into the availability of RO or de-ionized at refillable water stations. I currently buy de-ionized at my local Whole Foods for 39 cents per gallon, but the biggest plus is that I can re-use my containers and avoid the container waste. De-ionized is simply RO that has been further purified by ion exchange and is comparable to distilled.

Many thanks! This was .95/gal which I was happy with but I will check the big store about 6 blocks away from here and see if they do refillable. Cutting plastic waste would be great.
Thanks!