I wonder then where you can get phosphate to add ...
You can buy a cheap package of trisodium phosphate cleaning powder at Home Depot. One brand name is TSP. Or you can buy the oldtime cleaner, Spic'n'span, which has a tsp component. Store it in bottles; it's not expensive to store enough for the rest of your life. Add just a few grains to your dishwasher product each time.
Any hardware store. Trisodium Phosphate, TSP. About $3.00 a pound.
No, I have no idea how much you would have to use, but it wouldn’t be a lot....
Your urine. Phosphate's recyclable, but a little complicated and messy...
Buy boxes and boxes of TSP (tri-sodium-phosphate) at Home Depot, Lowes, local hardware stores.
I don’t know how to mix it with non-phosphate products, but that’s the phosphate that will soon be missing from damned near everything.