Check out "
SpectraPure."
They have a good range of products advanced or commercial growers who intend to purify their water. They retail directly too, so if you have any questions or concerns, they're in a much better position to help.
I have used their product for some time with no problems. But there are plenty of comparable brands.
***The most important thing is to determine whether or not your water includes monochloramine, which is an alternate water sanitizer to chlorine. Though chlorine is easily filtered out, the system needs to include a deionization chamber to remove the chloramine.
Good luck.