Does RODI filtration remove chlorine/chloramine?

[fishyjoes]

My water source report says 1ppm chloramine.
I went with double carbon blocks because the additional cost of the second carbon block is worth it to me as a safety factor.

 

[Malcontent]

Here’s the latest water report available from my town. Neither chloramines nor phosphates are mentioned. Edit: after a little research it seems that chlorine vs chloramine use is an either/or thing. Correct me if I’m wrong.

Water tested at the tap only addresses lead and copper. Doesn’t mention anything else. So now I have more questions

Here’s a link to the report if anyone cares to take a look and tell me what they think

https://www.valparaisoutilities.org/DocumentCenter/View/1483/2024-Water-Quality-Report?bidId=

Chloramine is reported as total chlorine to the EPA so sometimes it will reported as chlorine in these reports to consumers. Judging by the range (0.2-1.3 mg/L) though, you probably have chlorine since chloramine won't be an effective disinfectant at 0.2 mg/L.

This all depends on how much chlorine or chloramines are used. 1 carbon block may be adequate for standard levels if your city goes off grid and dumps a truck load in you may need another in line to provide the surface area to remove it from the water.

Rest assured this does not happen.

BTW, some municipalities run extra chlorine to flush their systems and this might not be solved by one pass through a single carbon block.

The purpose of flushing is remove sediment. Some chloraminated systems can't control nitrification without switching to chlorine for 1-2 weeks a year. If they adopt this strategy then they often combine the sediment flushing with the switch to chlorine. No elevated levels of chlorine are used. In fact, they likely use less as it's a better disinfectant than chloramine. It's also easier to dechlorinate chlorine or to remove it with carbon. During flushes you can be less vigilant about chlorine.

Any cheap total chlorine test kit will reliably test both chlorine and chloramine.

Don't those tests start at 0.5 mg/L? They can't detect the levels that could be toxic to fish.

Many water systems rotate chlorine and chloramine - typically annually. chlorine is strong and acts fast, chloramine is less reactive, has less by products and lingers. So it makes its way much further into the system with a lot of residual action. So Chlorine for basic water quality and then a run of chloramine for a while to break down biofilms and keep the entire system clean.

A common misconception is that the switch to chloramine is to have a disinfectant that doesn't degrade as quickly. This issue is easily addressed by using multiple chlorine injection sites. The main reason for the switch to chloramine is because the system exceeds the EPA limits for carcinogenic disinfection byproducts when using chlorine. Chloramine mostly avoids this issue but creates a new problem: nitrification within the system. One way to control this is to switch to chlorine for 1-2 weeks a year.

 

[Malcontent]

My water source report says 1ppm chloramine.
I went with double carbon blocks because the additional cost of the second carbon block is worth it to me as a safety factor.

I test chlorine with a Hach DR/900 or equivalent which can reliably detect levels as low as 0.02 mg/L. I have about 1.5 mg/L chloramine.

With a 75 gpd membrane, I needed 3 blocks of carbon otherwise I'd have to change the carbon too frequently.

When I added a 2nd membrane and a booster pump, I had to go to 5 carbon blocks.

The recommended contact time for chloramine is 5-15 minutes which I'm pretty sure I'm still falling short of even with 5 blocks. Having relatively low chloramine levels helps but I also add enough dechlorinator for 0.04 mg/L chloramine in the end.

 

[BeanAnimal]

A common misconception is that the switch to chloramine is to have a disinfectant that doesn't degrade as quickly. This issue is easily addressed by using multiple chlorine injection sites. The main reason for the switch to chloramine is because the system exceeds the EPA limits for carcinogenic disinfection byproducts when using chlorine. Chloramine mostly avoids this issue but creates a new problem: nitrification within the system. One way to control this is to switch to chlorine for 1-2 weeks a year.

Thank you for correcting any misinformation... that has greatly expanded my understanding.

Our water system is owned by "American Water" - I think we get notices when the make the switch, but I can't remember if it is in the bill or on the annual water report.

 

[twentyleagues]

Chloramine is reported as total chlorine to the EPA so sometimes it will reported as chlorine in these reports to consumers. Judging by the range (0.2-1.3 mg/L) though, you probably have chlorine since chloramine won't be an effective disinfectant at 0.2 mg/L.



Rest assured this does not happen.



The purpose of flushing is remove sediment. Some chloraminated systems can't control nitrification without switching to chlorine for 1-2 weeks a year. If they adopt this strategy then they often combine the sediment flushing with the switch to chlorine. No elevated levels of chlorine are used. In fact, they likely use less as it's a better disinfectant than chloramine. It's also easier to dechlorinate chlorine or to remove it with carbon. During flushes you can be less vigilant about chlorine.



Don't those tests start at 0.5 mg/L? They can't detect the levels that could be toxic to fish.



A common misconception is that the switch to chloramine is to have a disinfectant that doesn't degrade as quickly. This issue is easily addressed by using multiple chlorine injection sites. The main reason for the switch to chloramine is because the system exceeds the EPA limits for carcinogenic disinfection byproducts when using chlorine. Chloramine mostly avoids this issue but creates a new problem: nitrification within the system. One way to control this is to switch to chlorine for 1-2 weeks a year.

You must work for them.
I know I have gotten differing levels of chlorine out of my tap so I guessed there where reasons to increase the dose. MY city never used chloramines.

 

[GARRIGA]

The purpose of flushing is remove sediment. Some chloraminated systems can't control nitrification without switching to chlorine for 1-2 weeks a year. If they adopt this strategy then they often combine the sediment flushing with the switch to chlorine. No elevated levels of chlorine are used. In fact, they likely use less as it's a better disinfectant than chloramine. It's also easier to dechlorinate chlorine or to remove it with carbon. During flushes you can be less vigilant about chlorine.

Specific to my tap water. Chlorine is elevated to the point it bypasses the carbon and affects the membrane and some have reported that getting past the membrane due to high levels. Just what I'm being told.

 

[Randy Holmes-Farley Verified Community Expert]

Don't those tests start at 0.5 mg/L? They can't detect the levels that could be toxic to fish.

If you are concerned about lower levels than the typical 0.5 ppm total chlorine, one can get test strips that detect much lower levels for less than $20.

https://sensafe.com/sensafe-total-chlorine-test-strips-pocket-pack/
Detects:

Method A: 0.0, 0.1, 0.2, 0.5, 0.8, 4.0, 10.0 ppm (mg/L)
Method B: 0.0, 0.05, 0.1, 0.15, 0.2, 0.5, 1.0 ppm (mg/L)

 

[rtparty]

I don’t know man. BRS is in the business of making money so my question is, is a 4 stage adequate?

Surely there are people running 4 stage units on city water and coming out fine

Lol

Carbon blocks remove chlorine and chloramines. Chloramines destroy the life of all the filters so you need 2 carbon blocks to be safe when it comes to chloramines. It’s not about selling things. It’s pure facts with plenty of info out there to show why

 

[fishyjoes]

I test chlorine with a Hach DR/900 or equivalent which can reliably detect levels as low as 0.02 mg/L. I have about 1.5 mg/L chloramine.

With a 75 gpd membrane, I needed 3 blocks of carbon otherwise I'd have to change the carbon too frequently.

When I added a 2nd membrane and a booster pump, I had to go to 5 carbon blocks.

The recommended contact time for chloramine is 5-15 minutes which I'm pretty sure I'm still falling short of even with 5 blocks. Having relatively low chloramine levels helps but I also add enough dechlorinator for 0.04 mg/L chloramine in the end.

If you are concerned about lower levels than the typical 0.5 ppm total chlorine, one can get test strips that detect much lower levels for less than $20.

https://sensafe.com/sensafe-total-chlorine-test-strips-pocket-pack/
Detects:

Method A: 0.0, 0.1, 0.2, 0.5, 0.8, 4.0, 10.0 ppm (mg/L)
Method B: 0.0, 0.05, 0.1, 0.15, 0.2, 0.5, 1.0 ppm (mg/L)

These two messages have made me reconsider my setup - and I'd like to say thank you to you both.

I wasn't aware there were cheap low range tests so I have just been changing my carbon blocks every 6 months.

I found this 30 pack on amazon for $10 so I ordered them and will test the output from my carbon blocks to see for sure whether my double carbon block setup is really sufficient or not.

 

[GARRIGA]

I test chlorine with a Hach DR/900 or equivalent which can reliably detect levels as low as 0.02 mg/L. I have about 1.5 mg/L chloramine.

With a 75 gpd membrane, I needed 3 blocks of carbon otherwise I'd have to change the carbon too frequently.

When I added a 2nd membrane and a booster pump, I had to go to 5 carbon blocks.

The recommended contact time for chloramine is 5-15 minutes which I'm pretty sure I'm still falling short of even with 5 blocks. Having relatively low chloramine levels helps but I also add enough dechlorinator for 0.04 mg/L chloramine in the end.

I've thought about the issues that perhaps going to higher flows would cause less contact time with chlorine removal. Used to use a camper carbon block for my FW fish room connected to the garden hose and open wide there would still be chlorine remnants and wasn't sure it was the carbon block itself or perhaps the flow rate. Chose that particular camper carbon block because it was rated for high flow rates.

Notice Jake Adams in his video about water where he had several carbon blocks and at first assumed he was perhaps looking for extended use but perhaps it was just extended contact time to remove chlorine. Guessing most may not be noticing the concern because perhaps their membrane is resolving it or not bothering to test the effluent or I was just assuming but based on your experience now feel more confident I nailed it and yet not something I've seen others discuss and most additional stage systems seem to be about more DI resin vs more carbon blocks.

 

[theMeat]

For all you guys having to deal with chlora-whatever
Get one of these. This is a six year. There’s also larger 10 year models available
https://www.homedepot.com/pep/A-O-S...e=1&gbraid=0AAAAADq61Udgnk0r_Me-tUxbTDQS__LJrYour coffee and showers will be much more enjoyable

 

[EricR]

Thanks for the info. My unit does have a carbon block filter.

So is there a test kit I can get for down the road to test for chlorine and chloramine? And how far down the road should I expect to start testing? And I’m referring to when the carbon filter needs to be changed

I periodically test total chlorine (with test strips) after carbon blocks (before RO) to make sure none is getting through the carbon blocks.
*I run 2x BRS Universal Carbon Blocks that allegedly handle chloramine also, as mentioned in post #4

I use these but any decent total chlorine test strip should be fine:
LaMotte Total Chlorine Test Strips

 

[Reefer911]

For all you guys having to deal with chlora-whatever
Get one of these. This is a six year. There’s also larger 10 year models available
https://www.homedepot.com/pep/A-O-S...e=1&gbraid=0AAAAADq61Udgnk0r_Me-tUxbTDQS__LJrYour coffee and showers will be much more enjoyable

Unfortunately I’m in an apartment. But I am curious to know what the installation is. Maybe I could plumb it in ahead of my RODI

 

[Randy Holmes-Farley Verified Community Expert]

Unfortunately I’m in an apartment. But I am curious to know what the installation is. Maybe I could plumb it in ahead of my RODI

It's just a big carbon block. Unless you want it for other reasons, normal carbon blocks will be cheaper in most situations.

 

[theMeat]

Unfortunately I’m in an apartment. But I am curious to know what the installation is. Maybe I could plumb it in ahead of my RODI

Way overkill for an rodi
Stick with carbon cartridges

 

[Besieged]

I don’t know man. BRS is in the business of making money so my question is, is a 4 stage adequate?

Surely there are people running 4 stage units on city water and coming out fine

My specific scenario, take it for what it's worth: I'm on city water, but I'm in an area about an hour outside of Atlanta. It's hard to call it semi-rural, there's not really any farming going on around here, but the official city population is barely over 10k.

My local water supply says they use Cl2 according to a 2022 report. The next town over uses NH2Cl. They may well rotate between them periodically, as others have mentioned.

My tap water reads pH ≤ 6.4, KH ~40, TA <40, Cl2 ≤1.5, NO2 0, NO3 0, GH <25. A generic handheld meter reports a TDS of 41ppm.

Before I got my RO/DI unit, I was running this 3-stage Frizzlife undersink filter for all my drinking/cooking water and freshwater tanks. Water coming out of it ALWAYS tested 0 Cl2. When I replaced the sediment filter after 6 months in my current home, I was surprised to note it was as white and clean as when I installed it: in my previous home in urban Atlanta, the filter was always positively covered in brown sludge after the same period of time.

My current BRS RO/DI is plumbed pretty standard: 1x sediment, 1x BRS activated carbon, 2x RO, 1x DI - I have two more external stages I haven't plumbed in yet. BRS TDS meter reads 33ppm in, and 0 coming out, regardless of whether I'm using the booster pump. Cl2 is always 0 coming out.

So... I'm on "city" water, if you want to call it that. It's reasonably soft, and assuming my TDS meter is correct, I guess pretty clean, and with a reasonably low Cl2 reading well within EPA guidelines.

So, FWIW the single sediment and carbon stage seems to be doing fine by me. YMMV, IANAE. Test your water - you can't manage what you can't (or don't) measure.

 

[Malcontent]

A cubic foot of Calgon Centaur is $7.27 / lb vs. $20 / lb for a chloramine carbon block so I'm switching after I use up all my remaining carbon blocks.

 

[GARRIGA]

Just got notified of chlorine treatment. No mention of levels other than we are likely to smell it although I'm guessing I could call or visit the website hoping for better clarity. Why having extra carbon blocks might not be a bad idea for those on tap.

IMPORTANT NOTICE
The City of Pembroke Pines will be performing a chlorination preventive maintenance procedure on our Water Distribution System. The procedure will run for three (3) weeks from MARCH 23RD, 2025 until APRIL 13th, 2025. During this period, the City's Drinking Water Distribution System will continue to meet ALL Federal and State water quality standards. You may notice a slight chlorine taste and/or chlorine odor in the water.
If you have questions, please visit our website at www.ppines.com/1515 or call the Utilities Customer Service Department.
We thank you for your patience and cooperation during this maintenance activity.

 

[1ocean]

guess I will be adding two more cartridges to my already 8 filter cartridge rodi. Will add then after the sediment filter and before the membrane.. any suggestions..send them to me...
Now I know why I was burning through resins so quick, Chloramine causing it ..Thanks for the info..
1. sediment
2 carbon
3 coconut carbon
4 rodi membrane
5 cation resin
6 anion resin
7 mixed resin
8 silicate buster.

 

[KStatefan]

guess I will be adding two more cartridges to my already 8 filter cartridge rodi. Will add then after the sediment filter and before the membrane.. any suggestions..send them to me...
Now I know why I was burning through resins so quick, Chloramine causing it ..Thanks for the info..
1. sediment
2 carbon
3 coconut carbon
4 rodi membrane
5 cation resin
6 anion resin
7 mixed resin
8 silicate buster.

Why do you need more?