I have a customer looking for a Deionising plant. He is looking for the output of 100 liters per hour. Output water is used in the manufacture of antiseptic liquid. Input water is standard household municipal water.
I suggest you take a first step by carrying out the physicochemical and microbiological analysis of the standard household municipal water. This will help you prescribe the type of treatment; chemical, ion exchange resins, RO or combinations, and design the stages with your team to process the water that will yield the required de-ionised water based on the mentioned capacity and required standard.
There are commercial de-ionisers for such small volumes. But all resins and RO of that size, will harbour bacteria. This will need to be UV treated and bacterial filtered to bring it to the standard required.
100 liters per hour will be a small system. May be RO followed by ion exchange resin. Envirogen Technologies has several options for these systems including continuous or demand feed systems.
Envirogen.com
Memphis Service Center at 2070 Airways Blvd. Memphis TN 38114
You need to define deionized water by using a conductivity or resistivity (TDS) value to determine level of quality. Then you can determine if it is RO or RO followed by a polishing DI tank/system.