CDS Longevity

Start with cold water/CDS solution. In an open container (the dog's water dish or your relative's cup/glass) and at room temperature, the ClO2 concentration will start to drop within a few hours. For your relative, I suggest an insulated tumbler or a beer koozie (cozy??) to keep the temperature down. Adding an ice cube will extend the time that the liquid stays below 50 degrees F. As for the dog's dish, it's easy enough to just add some more CDS a couple of times a day. CDS is incredibly cheap when you make it yourself.

Sometimes I use a small handheld humidifier with about 75 ppm CDS solution in it. When I leave it out for 24 hours at room temperature, I find that the CDS concentration drops to about 25 ppm. I just add a few more ml of CDS to it and I'm good to go.

I use an insulated stainless steel tumbler with chilled CDS solution, and add an ice cube or two. By the time the ice has melted I'm finished with that serving, and pour myself another. I use 18 ml of CDS in each liter of cold, filtered water and drink it all day, every day. My understanding is that CDS doesn't react with stainless steel or glass..

Jim