[Scott Dean]

I've been looking over a few scenarios for a ro fitted into the van, i have a major issue that my current layout wont really accommodate a 40/40 but i have the room for two 40/21's one above each other...

on to my question baring the plug and play aspect of the EZ Pure does anyone have any experience with it, amount of water produced, robustness etc?? It seems the more logical option as two 40/21's from gaps water would set me back £600+vat just for those without pre filters... 

am i right in saying that two 40/21's would reduce my waste water (from 50% to 35-40%) but slow the production rate??

[Alex Gardiner]

You can have twin ROs plumbed in in two ways.

1. In series with the waste from the first one feeding the second one. This usually gives a waste ratio of 35-40%. This does only give you a production rate of about 70% more than a single RO (see chart below).

2. In parallel with the feed splitting and feeding both ROs independently. The advantage of this is that you will usually achieve 100% more production than a single RO (see chart below) and the quality will be slightly better. The waste Ratio will rise to about 50-60% though.

Here is a chart showing the production rate and ppm rejection of a single EZ-Pure (HF5 4021) on various pressures of input water.