What are the best water ionizers for 2021?

In all the years that I've been selling water ionizers I've not come across a better water ionizer design than the  AlkaViva H2 series water ionizers. The reason I say this is that not only do these water ionizers deliver among the best levels of H2 (antioxidants), but they also all have strong enough water cells to withstand the force of constant water pressure (such as what one needs for under-sink installation or for any kind of direct-connection to the plumbing). 

Though I think great performance is one of the most compelling reasons to choose a water ionizer. This video compares the performance of several of the best water ionizers.

Installation options are something all buyers should seriously consider. 

If you plan to hook up your water ionizer to the faucet with a diverter, then almost every single water ionizer I sell would be close to equally great with each other. (Note: These water ionizers have many other differences, and to be sure, you should refer to my  Water Ionizer Comparisons page before you buy.)

But, if you plan to set your water ionizer up with a direct water-feed line or under the sink, beware. I've seen many water ionizers develop a leak, sometimes years after the purchase. Even though it's just a slight, drip-drip, it's still a leak, and that's bad. Most manufacturers do not warrant your machine against eventual leaking if it's hooked up to direct-plumbing. Even if in the manual it tells you how to directly-plumb it, it doesn't mean you are protected forever. In other words, if you develop a leak from direct plumbing, you would be advised to hook it to a diverter, so it would no longer leak for you. Or, another popular option is to install an  external shut-off. 

Direct-Plumbing Recommendations for Popular Water Ionizers:

• Delphi H2 Water Ionizer This is the only under-sink water ionizer I recommend. It's really the best in every way.
• Vesta H2 Water Ionizer You can freely connect this water ionizer directly to the plumbing or by using an authorized under-sink kit you can freely install it under your sink.
• Athena H2 Water Ionizer You can freely connect this water ionizer directly to the plumbing or by using an authorized under-sink kit you can freely install it under your sink.
• Ionia's Super-S12 Ionizer This ionizer cannot be installed under the sink, ever. It is fairly new (since 2020), and though I personally use this model and haven't seen any issues with direct-plumbing of it, I can't guarantee that over time it won't develop one. 
• Smart 9P Water Ionizer I don't recommend direct-plumbing this water ionizer. It's one of the best water ionizers I've ever tested, but I have seen it develop a leak after months of being directly-connected (under pressure) to the plumbing. You can direct-plumb it, because it has a flow-control knob, but then you're taking a chance on it eventually developing a leak. It would never be appropriate to install this water ionizer under the sink.
• Melody II Water Ionizer You can freely connect this water ionizer directly to the plumbing or by using an authorized under-sink kit you can freely install it under your sink.
• Athena Classic Water Ionizer I used to recommend direct-plumbing this water ionizer or even installing it under the sink, but in a few cases I have seen it develop a leak. This was after years of being subjected to direct-pressure. You can direct-plumb it, but then you're taking a chance on it eventually developing a leak. I no longer recommend to install this water ionizer under the sink, ever, for this reason.
• Nexus X-Blue Water Ionizer This ionizer should never be installed to direct plumbing or under the sink.
• Enagic SD501 Water Ionizer This ionizer should never be installed to direct plumbing or under the sink.

Antioxidants in Ionized Water

The water ionizers, listed above, all get great test results for antioxidants. Here is a recent video about that:   Water Ionizer Comparisons ORP & H2 Levels for 9 Best Water Ionizers. 

Even the least expensive water ionizer I sell gets great antioxidant-levels. In other words, you don't have to spend $5000 or $4000 or $3000 or even $2000 to get a really good water ionizer. Look at the above video to see this. If you are okay with sitting your water ionizer on the counter-top, next to the sink, and connecting it to the faucet (as most people do), then almost any of the water ionizers I sell should be good for you.

Continuous-Cleaning in a Water Ionizer

Continuous-cleaning is something really important to look at when you're buying a water ionizer too. Does the water cell have continuous-cleaning, or is it just some form of regular cleaning? This will determine if that water ionizer is going to scale up over time. This picture shows the water ionizers' water-cells on the right are the ones with continuous-cleaning.

Water Filtration in a Water Ionizer

The best water ionizers also use the best filtration technology. Some companies have such poor internal-filters in their water ionizers that they have to give you external filters to make up for it.

There are quite a few water ionizers that come with good filtration, and if filtration is really important to you, you should check out  ultra water filtration, which is miles ahead of all the other filters. AlkaViva water ionizers and Jupiter water ionizers are both capable of using UltraWater filters.