RO or RO/DI ?

[bglass77]

I was recently gifted a RO/DI water filter. I have a couple of questions about it:

1. I've heard that it's better to bypass the DI section. Is that true?

2. My current water in Vancouver BC is already pretty good:

Calcium = 2.4ppm
Magnesium = 0.3ppm
Sodium = 0.9ppm
Sulfate = 0.8ppm
Chloride = 0.6ppm
Bicarbonate = 7.9ppm

TDS on the above water reads 10ppm

There is Chloramine in the water, so I still need to use the RO filter of course. Since my tap water is already so low in minerals, am I safe to assume that running it through the RO filter will essentially give me "zeroed out" water? A TDS reading on the RO water reads 0ppm.

 

[ajdelange]

I was recently gifted a RO/DI water filter. I have a couple of questions about it:

1. I've heard that it's better to bypass the DI section. Is that true?

Only in the sense that it is not necessary in most cases as the RO removes enough of the minerals in nominal water supplies that they can be considered 'ion free' at least in the brewing context.

2. My current water in Vancouver BC is already pretty good:

Calcium = 2.4ppm
Magnesium = 0.3ppm
Sodium = 0.9ppm
Sulfate = 0.8ppm
Chloride = 0.6ppm
Bicarbonate = 7.9ppm

TDS on the above water reads 10ppm

You can bypass the RO part as well.

There is Chloramine in the water, so I still need to use the RO filter of course.

No, you don't really. The system most probably has a carbon filter in it one of whose functions is to remove chloramine. That should suffice. Or you can bypass the whole system (RO, DI and filters) and just add a Campden tablet. That takes care of the chloramine and only adds small amounts of ions. The water is still essentially 'ion free'.

Since my tap water is already so low in minerals, am I safe to assume that running it through the RO filter will essentially give me "zeroed out" water? A TDS reading on the RO water reads 0ppm.

Yes, if you want really pure water this feed passed through an RO system should give it to you. You can get even purer water by going through the ion exchange filters as well. You don't have to worry about them becoming exhausted any time soon as the RO water will be so low in ion content.

 

[GotPushrods]

Put that on eBay and buy a 1000 year supply of Campden.

As far as brewing is concerned, the water out will be effectively no different than the input water. It's really a waste considering a fraction of a Campden tab will dechlorinate in seconds.