Calibration for a reverse osmosis water system

#1: Post by **razor488** » September 3rd, 2020, 11:59 am

I have an RO system that is under my kitchen sink that has been in disrepair since I moved into my house. I have a water filter company coming out next week to replace the filters and get it back up and running.

What should I tell the contractor as far as what I need my PPM to be? Any other special information I need to tell them for what I am looking for out of the filtered water? I plan to get a BDB.

Thank you,

#2: Post by **Nunas** » September 3rd, 2020, 6:21 pm

Most of those little under-the-counter RO units have no adjustments. You get what you get. You can install a bypass line with a needle valve so that you can blend back in a small amount of source water with the product water. Any good plumber should be able to do this for you (or you can do it yourself). If your RO does not already have one, you might install a boost pump by adding a permeate pump (think turbocharger is you're car-savvy). See this article https://www.wecofilters.com/blog/post/b ... stallation I have one in both my RO systems and had one in my motorhome.

September 3rd, 2020, 11:02 pm

And if it's been not working and properly maintained it may have some yucky bacteria in it. We decided to replace ours. If you don't do that make sure it gets a great and thorough cleaning.

September 3rd, 2020, 11:20 pm

razor488 wrote: What should I tell the contractor as far as what I need my PPM to be? Any other special information I need to tell them for what I am looking for out of the filtered water? I plan to get a BDB.

Thank you,

The repair tech ought to be able to give you guidance on how to sterilize it. There are also online guides. IIRC it involves running the system with bleach and no filters in place, and of course proper rinsing.

As for having a minimum of conductivity so that the BDB's sensors work properly...

You could:
1) get a cheap TDS meter and check the TDS of the water coming out of your RO spigot. Often it will be up to ten percent of the the hardness of the input municipal water. That might be enough if you're in a hard water area

2) The needle valve idea, but some of what you are adding back is likely to be scale minerals, Ca and Mg. So scale might become possible, even if much less aggressive than with no treatment at all

3) Save the RO for drinking and Buy distilled water and add some buffer to it. Either baking soda or potassium bicarbonate. Tiny amounts... 100mg/l. Or make a concentrate of 100ml water and either buffer. Then add 1ml of buffer per gallon of distilled water. 1ml of water is 1g.

-Peter

#5: Post by **homeburrero** » September 5th, 2020, 6:00 pm

Some RO systems on high TDS water let enough through to allow the water sensors to work. It depends, and some sensors/controllers have adjustable sensitivities, but 10-20 ppm should be enough for that.

The bigger issue for an espresso machine is the low pH and low alkalinity of the water coming out of the RO. It's primarily a corrosivity concern. The usual way of dealing with that is with a remineralization filter. A simple calcite filter will help with that. It won't add much, maybe 20-60 ppm of CaCO3, and the amount that it adds depends on the flow rate and the pH of the water. Fortunately, it adds more mineral when the pH of the water going through the cartridge is low. You could use a remineralizer that uses calcite along with some 'Corosex' which are magnesium oxide beads that add a little extra magnesium hardness and bicarbonate alkalinity, raising the pH higher. I'd suggest being cautious about any cartridges that purport to make the water highly alkaline. (Highly 'alkaline' water for drinking is a current fad, and I think some remineralizers that are marketed for that purpose may over-correct minerals in producing a high pH. )

The needle valve bypass would be another way to remineralize, but that would require more attention to getting and keeping the blend right. And in some cases (for example when the tap water's chloride ion content exceeds the bicarbonate ion content) may be inadvisable. You can buy RO systems that come with a blending valve, but most of them are high capacity and high cost. The cheapest I've seen is this one: https://www.craftbrewwater.com/collecti ... ding-valve

Using the RO as a purified water source and mineralizing that in containers per recipes (rpavlis, barista hustle, etc) is a perfectly good option in my opinion.

September 15th, 2020, 10:51 pm

I set up my BDB for the first time and used the water test strip on my RO water. I got one red square. Does this mean my water has enough ppm for the BDB to operate effectively? Should I get a cheap TDS meter just to be safe?

One note - I saw the water filter contractor test my tap water and it was 260 PPM. The RO system before he replaced the cartridges was 60ppm. I didn't see a test after the cartridges were replaced.

Oh and one more edit - I have noticed that after using the RO water in the Breville You Brew - the coffee doesn't taste great... Not sure how to describe it... maybe flat? I noticed this as soon as I switched from tap water to the RO water.

Thanks,

September 16th, 2020, 9:56 am

So you are back in business with a freshly serviced RO system, correct? In this case, it's probably worthwhile then to use a cheap TDS meter to make sure you are getting at least 30ppm or more. (It might be OK at 20ppm too. I just don't know.)

You are not the first person to have claimed the ability to taste more from harder water. If that is the case, you are going to have to look at additives like sodium or potassium bicarbonate or a pre packaged product like Third Wave Water.

-Peter

September 16th, 2020, 10:33 am

Peter,

What do you think about adding this filter to my RO system? I have a cheap TDS meter on order from Amazon.

https://www.freshwatersystems.com/produ ... ter-filter

Thanks,

September 16th, 2020, 11:12 am

I like the concept of remineralization. But for example, that cartridge does not say what it adds, just what it removes. Someone here who uses remin cartridges with RO might have more to say than me.

If you are one of the sensitive tasters who can for sure tell the difference, and it seems like you might be, You might do yourself and the rest of the community here a service if you were game to risk the $33 and try it. And report back what you think about the taste, both with and without. Also take measurements with your TDS meter with and without the remin cartridge and report what they say.

Unfortunately this can become a rabbit hole when you don't mix your own water. If your TDS goes up, you don't know what components it consists of. If it goes up because of re addition of Ca and Mg, you might be putting your machine at risk of scale damage. But it is also possible for your TDS to go up NOT from Ca or Mg. This is the case with me and my softener. My tap water TDS is about 140ppm with a lot of it being Ca and Mg. After my softening filter my TDS goes up to 190ppm but NONE of it is Ca or Mg. So, I have an $80 testing kit, the Hach HA71A that tells me when my softening filter is beginning to pass Ca and Mg, and by how much. See how this rabbit holey this can get?

If my BDB weren't plumbed, I would use distilled or RO and add K-bicarb or Na-bicarb as necessary. If I could detect a taste improvement (and I'm not sure I can), I might consider one of the Barista Hustle recipes or Third Wave Water, and keep a close eye for scale. Not everybody has that sensitive a level of taste.

-Peter

September 17th, 2020, 6:44 pm

razor488 wrote:What do you think about adding this filter to my RO system? I have a cheap TDS meter on order from Amazon.
https://www.freshwatersystems.com/produ ... ter-filter

That cartridge, and others like it that promise a boost in pH, and a promise to produce 'alkaline water' without specifying somewhere what media they contain are to be avoided. A high pH can be achieved by using a magnesium oxide media that would overcorrect the water for espresso machine purposes.

A filter that's primarily calcite, or ground marble, is generally a safe bet, as would be one that includes a small amount of Corosex media. (Corosex is a trade name for a magnesium oxide remineralizing pH correction media.)