The union that takes place when a chlorine gas is injected into drinking water with a ratio of ammonia and with the correct PH level Monochloramines are formed and hopefully not Dichloramine or Trichloramine.

So Monochloramines have there place in the disinfection process to deliver safe drinking water to our homes, our charge then is to treat the water at our homes to remove the transport safety vehicle Monochloramines from our drinking water. We have then found a very efficient way in our filter or gravity purifier to remove the Monochloramines successfully.

We learn that the bond has been broken between the chlorine and the ammonia bringing and end to the Monochloramines strong hold, the chlorine is converted to a safe form of chloride but the ammonia is now left behind or protonation may have occurred to form ammonium.

What now takes place in our drinking water?

The following is an extract to help answer that question

What happens with ammonia ions in tap water after they are separated from chlorine?

Question;

Tap water is increasingly treated with chloramine which is composition of chlorine and ammonia. Chlorine can be removed by catalytic activated carbon and ammonia ions are then left. What happens with them in the water? Do they bind with something or are they left in ionic form? How quickly they evaporate at room temperature?

Answer;

Chloramines (mono-, di-, and tri-) are used as a disinfectant for drinking water treatment (the source water, not the tap water) - this process is called combined chlorine. Upon contact with pathogens, organics, etc., chloramine is reduced to chloride (not chlorine), ammonia, and hydroxide. However, this half reaction is for alkaline conditions. The pKa of ammonia is around 9.4, so around circumneutral pH, some ammonia will exist as ammonium, the protonated state.

So, will activated carbon (AC) remove the products? First, we need to clarify something about AC - it is not catalytic, it is a physical adsorption removal process. AC will remove chloride ions, but it will not remove ammonium. Ammonia is quite volatile and will move from the water to the gas phase if e.g., a pitcher of water is left at room temperature. If you wanted to remove ammonium as well you could use something called biologically activated carbon (BAC). One last note, chloride will not "bind" will AC, it will be adsorbed through electrostatic forces.

Reference Source

Thoughts of conclusion

Based upon the fact that ammonia is "quite volatile" and will move to the gas state phase and ideally dissipate if left in a vessel at room temperature.

Could a gravity water purifier bottom reservoir facilitate this stage of the expulsion of the ammonia given the time that it is sitting until the time the user dispenes for use.

Compare then another user taking a glass of water directly from a filtered water source that has a very capable catalytic carbon or even and RO (reverse osmosis system) that has successfully broken the bond between the chlorine and the ammonia but not achieved the time needed to allow the ammonia to enter the gas phase prior to consumption? 

Fish tank owners recommend ageing their water for at least 24 hours, fish are a very good barometer for water quality, we can learn alot from nature.  

PS. Berkey reduces Chloramines to below lab detectable levels, we can confirm that by overwhelming smell left behind in the top reservoir, I am glad it is there