Having dealt with these chemicals for 35+ years in a variety of water treatment applications, it is my considered opinion that there is value to the product, but it really isn't worth the bother and it is incredibly expensive for what you get, and there is a strong element of risk. You will find much more benefit from cheaper and more common treatment methods without worrying whether if what you have is fresh or will work.
The trick to what they are talking about is to kill off the pathogens, and then store the water in such a way that it is not possible to introduce new pathogens. Keep water in an airtight container and out of the sun, and you've prevented it from being recontaminated. It is your water storage method that does this, not this or any other product. Any product that would itself keep your water pathogen-free for 5 years without these storage procedures would be so toxic that you couldn't drink it.
That said, sodium hypocholorite works. It also actually is household bleach (go look at your Clorox bottle), and it really doesn't matter if they put a stabilizer in it or not. Sodium hypo is most stable at 5.25% (household bleach strength). It will be at strength for a year or more if left cool and in the dark and it will be close to that strength for several more years. A half cup of bleach in 55 gals of clean and clear water will do the job. Seal the water and store it. Done! Doing it this way will also keep your water drinkable for 5-10 years.
If this product needs stabilizers in it, it's because their bleach has a shorter shelf life or because they are using it as a marketing gimmick. My concern however, is that stabilizers also add another chemical to what you are drinking. Using cyanurates (for example) works to stabilize a 7-8% bleach, but it has also been identified as a carcinogen in high quantities. Keeping water safely doesn't require stabilizers. It just requires sanitizing it once and storing it properly... something you have to do with or without this product. The only reason to have stabilizers is if the product itself is unstable. If that's the case, that would concern me because products that break down often form other really nasty contaminants and are largely unpredictable if they are ingested.
Normal bleach is not that unstable that stabilizers are necessary. Unfortunately, this manufacturer doesn't tell us what stabilizers are in it, why they have to be in it, or what the health risks are. Essentially, they are telling us, 'Here's some stuff to drink, we are not offering you any analysis of our claims or ingredient list, but drink it anyway.' I am not suggesting that it is unhealthy, but there is nothing here but your own inference that it is safe.
Do yourself a favor and keep a couple gallons of bleach around the house, and if you are concerned about something more, go invest in a quart of 40% pool algaecide. Choose the one with the ingredient n-alkyl dimethyl benzyl ammonium chloride. It sounds nasty but you deal with it every day in very low doses in commercial kitchens, bathrooms, locker rooms, and pools. A .06% is health department certified to kill off all pathogens, which means that a quart of 40% will create 650 quarts of disinfectant, and you can use 1 qt of that to treat 55 gallons of water. That is far more than you will ever use for water consumption, so keep the rest around to spray down surfaces and kill bacteria, molds, and mildew. It's used a lot in gymnasiums on hard surfaces to wipe out athlete's foot fungus and other sources of infection and smell. As for the smell, it leaves kind of an almond scent behind.
Such products as the ones I'm talking about have also undergone extensive testing before being deployed and authorized for use in pool water that can be drunk and around food products. The description of this product bears no such claim.
***EDIT***
This edit is added because there are apparently some readers who think this is some sort of a water taste review. It is not. This IS NOT about taste. Other than potentially being indicative or a confirmation of what's in the water, taste is irrelevant in survival situations. Forget about the taste. But if that is still all you can think of, then add some sugar and be happy.
This review is about the claims made by the product, how irrelevant they are to real world situations, and that there are chemicals left behind to be consumed by you and your family when you drink this water. Focus on the fact that you don't know what these chemicals do to your body when they are ingested, and the fact that they are not necessary to keep water healthy.
I also wanted to point out the potential dangers of the some water barrels. It is important that you find product that complies with U.S. Food and Drug Administration regulation 21CFR 177.1520 (1) 3.1 and 3.2 for storage of potable water, and has not been used for other purposes before you bought it. Plastics come in varying qualities and for different purposes, and some leech process chemicals or components. If it has been used for any other purpose, it could have absorbed some of that and not be able to be adequately cleaned out. Again, for you people who think this is about taste, it is not. Use what you will and then let the rest of us know when your kidneys are shutting down.
Even if your water storage is brand new, they can release gases for awhile. Maybe they are okay, maybe not. Maybe they give you the runs or just make you feel like you ate a wad of plastic wrap. Only experience will tell you if you made a mistake, and then it's probably too late. My recommendation is that you do a complete drain and refill at the 6, 12, and 24 month mark at a minimum, and then every 24 months after that. Be sure to rebleach water going back in and store them properly. Yes, it's a lot of work, but that doesn't make it any less advisable or beneficial.