I have a family member that is immune suppressed
and we have been told that any home R/O unit produces water that is completely safe for drinking by anyone suffering permanent or temporary immuno-suppression.

Provided proper maintenance, if the R/O System has full NSF Certification, a immuno-suppressed individuals may be safe drinking R/O permeate provided they received daily calcium, magnesium and other mineral supplements. For complete safety the R/O's permeate should be tested monthly for Heterotrophic bacterial colony growth. However, many home R/O units do not have full NSF Certification of membrane, media and the system. In addition, the carbon and prefilters are rarely changed before 1,000 or the 3,000 gallons maintenance requirements. As such, chlorine damages the membrane each time allowing pin holes to form upon the membrane's 3-5 µm (micrometer) thin film surface. Next, during routine maintenance the membrane must be cleaned via acid then a base followed by a sterilizing solution. Hetertrophic bacteria grow in both the prefilter & carbon media which fouls prefilters and contaminates/damages the very thin (3-5 microns) R./O & Nano membranes. Two of the major O.E.M. Manufacturers: Osmotics and Dow's FilmTech, provide warning notices that low pressure R/O Systems are incapable of producing sterile filtrate due to membrane defects-pinhole formations. These pinhole formations allow bacteria, endotoxins and pyrogens to contaminate the permeate. The passage of E.Coli and other Coliform bacteria will damage an immuno-suppressed individual's long term health. Giardia or Cryptosporidium oocysts can kill an immuno-suppressed person. Our Kold Ster-il® 3 Canister Ssytem provides (2) two separate methods of protection for an immuno-suppressed individuals drinking water. First, is a 0.20µm filter bag which barrier 99.99% restricts: Giardia, Cryptosporidium oocysts, E.coli, Coliform bacteria, bacterial endotoxins, biopolymers, particulate phosphates, algaes, fungi and diatoms. This submicron filter bag is fully exposed to chlorine, chloroamine or ozone water disinfection. Last, is the 0.50 µm Carbon block fully rated under NSF Standard 53 (appendix) for Giardia & Cryptosporidium oocysts providing 99.9% restriction. Only Kold Ster-il® provides double filter media protection.