The Delphi H2 is specifically designed for undersink installation. We recommend that one as the best choice for undersink water ionizers. Most other water ionizers, made for countertop installation, may have issues with the extra pressure put on the water cell. 

Undersink Kits: There are a few counter-top water ionizers that are strong enough to be converted to undersink water ionizers if you buy the proper undersink kit and faucet. When you use one of these water ionizers with a conversion kit you do not have full functionality at your fingertips on the faucet. The way it works is that the machine is in "sleep mode" when water isn't flowing and turns on automatically when you start the water flowing. If you always use the same level for pouring, this system will work fine for you. Only the H2 Series water ionizers have strong enough water cells to work well with undersink kits.