Why not get a gumtree small bar fridge and sit it beside the kegerator for your cold water storage?
I don't really have room for another bar fridge in the garage, nor do I really want to run yet another electrical appliance. If I did pick up another small fridge, I'd probably want to use it as a temp controlled brewing chamber for beer.
Ok so with my experience running two soda water kegs simultaneously for the past 5+ years, one chilling and carbing while the other one drinking, it takes about 48hrs at 30psi to be suitably fizzy. This is heavily dependent on adequate headspace in the keg e.g. 2L or so. The more headspace the quicker it will work. (No carb stone on this setup).
I've installed the carb reactor and been running it for about 5 days.
We normally drink about 10L a day. I've had to increase the pressure to 45psi and turn down the temperature of my kegerator to cope with the addition of ambient water to our drinking keg (28c).
The benefit of this system is that I only have room for 4x kegs in my kegerator and two of these were previously soda water, so I don't have room for a pre-chilling keg, although I thought with one of the PET tee-pieces e.g.
PCO 1881 CARBONATION CAP TEE PIECE https://www.kegland.com.au/pco-1881-carbonation-cap-tee-piece.html
one could use a small vessel with a larger surface area to volume ratio as a daisy-chained pre-chilling vessel prior to the keg. This was my next step if pressure increase to account for less carbonation time didn't work.
Doesnt the new ambient water come in at the top? In theory it should stay up the top while it chills and carbs and you pull from the nice cold carbed bottom water? Maybe it doesnt work like that in practice :/ I have no idea as ive never carbed like that but am thinking of setting up a continuous system with the reactor lid.
So I pumped the pressure up to about 30 PSI, gave the keg some shaking, venting, shaking, venting etc for about 10-15 minutes and then gave it another 24 hours to carb up. It's going nicely now. It's not super fizzy water, more "lightly Sparkling". I'm not sure if that's because I need to up the pressure more or if it's losing pressure as it comes out of the tap and into the glass. I'm using a standard water filter tap rather than any kind of beer or soda tap. It gushes and sputters out pretty violently and I can get a fair bit of foam in the glass, so I suspect it's just losing its carb pretty quickly. May pump it up to 40PSI and see if that makes any difference.
However, it's pretty fantastic and it's been getting a lot of use with the hot weather in Sydney this last week. It's super convenient to pump a few squirts of soda stream syrup in a glass, add soda water and drink. I'm not normally a plain unflavoured soda water person but a glass of chilled soda water before bed is pretty refreshing and hydrating.
We're going through maybe 2 or 3 litres a day, and it doesn't seem to have any trouble keeping up. Because I'm only drinking a glass at a time, you're removing maybe 300ml from 19l and replacing immediately. It doesn't seem to be enough to dramatically impact temp or carb in the keg.
The one thing that's a bit of an annoyance is wasting warm soda with every glass. Because the line is plumbed through the back of the kegerator and through the wall, there's about a metre of line that is outside of the fridge. The water in this warms up pretty quick, so I generally have to vent the line until the water runs cool. It's about 130-150ml of water each time. Fortunately, it's pretty easy to do because the filter tap is thin metal. You can see it frost up instantly when the cold water starts running through it, so there's a super-easy visual indicator. I've been spit-balling ideas of trying to wrap the soda line in a thicker insulated hose and pushing cold air into it, similar to how the built-in chilled font in the Kegerator works, but I'm not entirely sure how that would work over the length of the line, and trying to pump air into both the soda line and the beer font. For now, 100ml of warm soda down the drain isn't the end of the world.
Next up, I need to figure out ratio's and measurements to turn the Gnome or Fermentap Root Beer concentrate into a usable syrup to make Root Beer by the glass. It's a lot more concentrated than SodaStream and doesn't have sweetener in it, so I need to do some maths to work out how much sugar syrup to add to it.