Difference between RO and DI

I would like to know what the difference is between RO and DI are they different cleaning sources or do they go together?

they are different ways to filter water and can be used together or seperate. check these out…

Which way is generally less expensive for the beginner and is more portable?

The set up for a DI tank is less expensive short term. If your tds is above 100 then the sooner you get an RO/DI cart the better for your long term costs.

I have yet to bring this up, but this seems a good time.

Our DI cart is perfect for this scenario. The ‘Reach’ 2 Stage DI cart converts into the R3(an RO/DI Cart) if you find that your business grows into it.

Now THAT is a great design. A good way for a business to make the most out of every dollar.


There has also been a lot of talk about a carbon prefilter for DI tanks.

The bracket that holds our prefilter on the R3 is available for the 2 Stage DI Cart to extend the life of the DI resin. This is available as an add-on or simply order your 2 stage DI cart with the prefilter installed. The DI carts are pre-drilled with holes for the bracket if the user wants to install it at a later date.

We will get this info on our site and make it available to WCR in the near future.

RHG leading the way once again! Well done Shawn, well done!

This question is not so simple to answer but I’ll put it in simple terms.

RO=Pure Water (Water is FORCED through a membrane that has super small holes in it. The holes allow the water to pass through the membrane but the holes a small enough to stop most desolved solids)

DI=Deionization exchange. This water is NOT distilled water, they should not be confused because they are not the same. Here’s a link to a wiki read on the subject. http://en.wikipedia.org/wiki/Distilled_water#Deionization

DI basicly changes the natural state of the water by reverseing the electron molecules in the water by using a resin. IE It takes a positive molecule and makes it a negative. Naturally the water will want to turn back to it’s natural state. How does it’ do this? It does this by pulling in as much minerals and junk that it can to try an get it’s minerals back. This is the process that actually cleans the glass. It’s the process that breaks down the dirt and debris on the glass.

The RO is mostly for rinsing the window and keeping it from streaking or spotting.

Both working alone produce great results. Both working together produce the same results. The issue comes from your tds. If you have high TDS you might want to go with an RO DI unit. If you have low tds you might want to go with just DI. It’s a cost thing. RO/DI units do not have to have their filters changed as much, compared to both systems working alone. RODI systems cost much much more then a DI system. But something you should keep in mind. You should not clean glass if your TDS is around 10 or so. It can spot. Keep in mind, that your TDS maybe differant then your customers TDS. Before you make a choice you might want to call your local water company to find out what the average tds in your location is. Reason being. If you use the DI unit at one customers home who has a high tds it will kill your resin. You could end up having to replace your resin more then you think which in the end might cause you to buy a RO unit.

Shawn is right on the money with that idea for his systems. Building a machine that allows for adding on systems as needed is really a great feature. Hope this helps.

RO will not remove all the “bits” from the water unless you are in a low TDS area in which case you are better off using DI to save on water.
When you have a high TDS reading you use the RO to reduce that by about 95% and then put that water through a DI unit to remove the last few bits. If you used DI only in a high TDS area you would use up your resin very quickly and so not so cost effective.

Most people use just 1 DI unit and will change the resin once the TDS starts to rise from 0. However there is still a lot of use in that resin…

For instance… If you have a tds reading of 200… water goes in through the RO and comes out at a tds of 10… You then put it through a DI to get to 0… but lets say you throw the resin away at a reading of 2… The resin isn’t fully used up as it is still removing 8ppm from the water… The resin is only 25% used up… Now if you feed the water through a second DI unit then the second unit is only removing 2 from the water and not 10… and your still getting pure water tds 0 out of the second unit… Carry on with this untill the tds of the water comeing out of the first DI unit is the same as the water going in… The resin is now fully used up… Then just swap the DI units around and refill the totally spent one… You will find you will get a lot more use from your resin and so save money and the enviroment as your dumping less resin. Yes you do need to buy a second DI unit and fill it with resin but with the savings you will soon recover the extra costs. Some people have claimed to be saving 50% or more on resin costs using the twin DI method…

Mr H