Hardcore! Where do you even get kegs of seltzer?
A kegerator setup has a CO2 canister, so a flat liquid is put in, all the hoses are set up, pressure is added, and as it sits the CO2 dissolves in the liquid, carbonating it.
Yeah its super easy I buy the 5lb Co2 canisters from the home brew store add normal tap water to the kegs and put it under 30 PSI for about 5-7 days. The CO2 dissolves in and I get carbonated water. I keep 2 hooked up so I can rotate them when I blow one and thats usually enough time to carbonate the next. The setup is a bit pricey I think it probably cost about $400 to get going and I was originally using it for homebrew but as Ive gotten older I cant really drink without messing up my sleep so ive switched over to just carbonated water.