How can I get HCl 20% to 30%?

I have a process and I get HCl 20% (with some impurities) and I want to put it at 30% for selling it. I thought about using HCl anhydrous (is so valuable in my process, so no), and HCl 30% (this one don't have impurities, so no), someone know a different way? Thanks a lot.