I've been using one cup coffee makers now for about 40 years.
I got this latest one because it was taller and I could fit my big 16 ounce mug in it.
I got it used from the Salvation Army store for $2.50
I of course, had to take my first one apart to investigate.
There is a one way valve below the reservoir that allows water into the heated metal tubing inside. When the water boils it is forced up through the tubing and into the basket but not back up into the reservoir.
Once the heated metal tubing is empty, gravity feeds more water down from the reservoir into the heated tubing.
I would just boil vinegar through it to clear the lime build-up then a few cups fresh water to wash it out.
I use RO water now and I never have to clean it.
RO water makes better coffee too.
This is my RO water set up,..
View attachment 168876
The RO filter was only $68 at the time but the cheap valve started leaking within a few months, so I bought a proper brass valve for ~$30.
The filter wastes 2 liters of water for every liter of RO water that it makes, and I couldn't bare to do that, so I routed the waste water to to my toilet tank and shut off the water feed to my toilet.
I feed the RO water into two plastic jugs above the toilet then rigged up PEX pipe to a valve above the kitchen sink.
View attachment 168878
Then I added an electric solenoid valve ($23) and a wind up electric timer switch ($27) so I can fill my toilet tank with exactly enough water without waste.
Which leads me to a question for you and
@PDoz ,..
I have a 3 stage RO filter, with a sediment filter as the first stage, an activated carbon filter as the second stage, followed by the composite membrane filter.
My tap water reads ~210 PPM TDS and my RO water reads ~12 PPM.
But recently, my RO water jugs are filling up with bubbles which I think means that my carbon filter is saturated and the chlorine is now getting through and degassing in my water jugs.
So my question is, what exactly are those bubbles?
Oxygen, CO2, chlorine gas? Or what?
You guys mentioned biofilm, and I was thinking that having the chlorine go through the membrane might actually be a good thing, and kill anything that might be growing in the membrane filter?
The filter specs say that the filter doesn't remove hydrogen sulfide from water, so I guess gasses get through any RO filter and need to be separately removed before or after filtration.
The PPM of my filtered water has remained the same since new so I know the filter is working and either the gas doesn't affect my reading or it degasses in the jugs.
Would chlorine getting into the membrane damage it? Or would it actually sterilize it to keep it clean and safe for drinking?
I can replace the entire filter for ~$70 or even try to repack my carbon filter as an experiment (I've got a couple of bags of activated carbon for aquarium use) or just leave it be and let it degass in the jugs?