Chlorine and chloramine

[goofiness]

Based on my readings at TFP, and the test kits, when there are measurable levels of combined chlorine, it means that there is likely some bad stuff in the pool that the FC level is not taking care of. Since using the TFP method for 3-4 years, life is pretty simple, my pool water is clear, no algae, FC level where I want it, and usually no measurable combined chlorine.

As I understand it, combined chlorine means there are chloramines present, which is bad. If that is correct, then why are municipal water districts using chloramine as a disinfectant, instead of chlorine?

Thanks.

 

[needsajet]

Just a newbie perspective... chloramines are an indicator and need to be interpreted. If there's leaves, dirt, bugs or bather waster recently introduced to the pool, there will be chloramines yet to be burned off, as part of FC (HOCl) doing it's job. I don't perceive it as bad unless it gets to CC 1.0 and even if that occurred I would think about what's been happening in the pool that day.

This link helped me get comfortable as I learned about pool chlorination and how it relates to drinking water regulation.
2. What are EPA?s drinking water regulations for disinfectants like chlorine? Drinking Water

 

[goofiness]

Thanks for the reply and the link. I must have a mental block on this subject. My question remains. According to the site in the link, the target maximum level of chloramine, when used as a disinfectant, is 4 ppm. Then why do we get upset when the level in our pools gets to be 1 ppm? Should we not be doing whatever we can to get that level up to 4 ppm?

 

[needsajet]

Based on my readings at TFP, and the test kits, when there are measurable levels of combined chlorine, it means that there is likely some bad stuff in the pool that the FC level is not taking care of. Since using the TFP method for 3-4 years, life is pretty simple, my pool water is clear, no algae, FC level where I want it, and usually no measurable combined chlorine.

As I understand it, combined chlorine means there are chloramines present, which is bad. If that is correct, then why are municipal water districts using chloramine as a disinfectant, instead of chlorine?

Thanks.

In your pool, some of the bad stuff is the chloramines. With FC is at a high enough level, there is sufficient HOCl to break down the chloramines (along with the breakdown of chloramines by sunlight).

Sorry, I'm no help regarding how chloramines work in potable water systems. I misinterpreted your question and should have stood clear for the chemists!!!

 

[JoyfulNoise]

This link will contain lots of information about drinking water and monochloramine - https://www.epa.gov/dwreginfo/chloramines-drinking-water

First off, let's keep this in perspective - pool water and drinking water are different things; we don't necessarily think people should be drinking pool water. So, as was mentioned in the reply above, when TFP recommends testing for a chemical and and recommends a specific level, we are doing it as indicator in order to help determine what the water quality is and what, if any, corrective actions need to be taken.

Second, the CC test in your pool kit is sensitive to combined chlorine(s) - monochloramine, dichloramine and nitrogen trichloride; some other chloro-organics will also register on the test. These are all collectively known as disinfection by-products, or DBPs. Monochloramine, when compared to the rest of the DBPs is the least nasty of the bunch. Some DBPs are incredibly irritating even at sub-ppm levels (nitrogen trichloride) and others can be carcinogenic. When monochloramine is found in pool water, the higher levels of FC will continue to oxidize it and convert it to dichloramine and then nitrogen trichloride. The last two have fairly high outgassing rates so, thankfully, their concentrations in pool water will be low. So, in order to have a pleasant swimming experience, you want the CC levels as close to zero as possible to avoid things like eye irritation (the primary cause of eye irritation in swimming pools is not pH but CC) or the "chlorine pool smell" that so many people associate with swimming pools and hate.

As for drinking water, you can read about monochloramine in the link above. Basically, water utilities will use a mix of different disinfection strategies to produce the safest water possible. At the plant they will use chlorine for primary disinfection but it does not last very long and it will create high levels of DBPs. So, in order to keep long distance pipe runs clean, monochloramine is used as a secondary disinfectant as it is much slower to break down and it will not create the same levels of DBPs as higher levels of chlorine will. By the time water is delivered to most homes, the CC level (monochloramine) is typically around 1ppm or less. My own tap water has 1ppm FC and ~0.5ppm CC when I test it. Standard carbon filtration pitchers (like a Brita filter) take those chemicals down to undetectable levels.

 

[goofiness]

Thanks for the replies, especially to Joyful Noise. That makes the issue understandable. We get water from a private well, which is untreated, but our son lives nearby, where the service recently switched to chloramine. I'll send him this post.
Thanks again.