[magic1]

guys, I'm in the process of doing a van set up. I've got a ro system set up. the tds of the pure water is 000. Do i need to fit a d.i. to polish it off?

if no, I've seen loads of set ups posted on the net that have both & was wondering why?

Thank in advance.

[U.S. wfp USER]

Your source water may have a low enough TDS to get it to 000 with only an RO unit.

If the RO does the job then why ad the extra cost.

Only issue would be that when the TDS starts to climb you will have to swap the membrane.  If you had a DI you could get more life out of the RO membranes.

[Dean Aspects]

also if the tds of the tap water is low (hard/soft) you maybe would only need di and then you would only need to change the resin dependent of course on the  tds of the tap water and how much you use per day