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This month's question: I heard that LA DWP and other municipal agencies are replacing chlorine with chloramines. What will that do to my beer? Should I make any changes in my brewery?

Most brewers know that chlorine can do two things to your brewing process:

  1. Keep your equipment sterile, which is a good thing.
  2. Generate foul-tasting byproducts, which can ruin your beer.

Hence, most brewers have sort of a love-hate relationship with chlorine.

Chlorine is added to the municipal water supply to kill bacteria, fungi, viruses and other health-threatening items organisms. This makes it possible to use municipal water to top up partial boil batches, rinse out your siphon hose and other convenient things. Without chlorine, we would have to boil every last bit of water that ever touches the beer, and rely much more heavily on other sterilizing agents such as iodophor. To the best extent possible, chlorine should be prevented from getting into beer. The reason for this is that chlorine can react with the myriad organic chemicals to create chloroorganics. Some of these compounds have strong undesirable tastes or aromas. Probably the most notable is chlorophenolic, which can form when chlorine reacts with the phenolic components of grain husks, particularly p-hydroxybenzoic acid. Other compounds that can form are simpler compounds such as chloroform.

The municipal process of disinfecting water can create similar chlorinated chemical compounds. Many chlorinated compounds are carcinogenic, so the city has been looking for ways to disinfect water without the use of chlorine. Chloramines fit the bill, so the city is currently in the process of phasing in chloramines and phasing out chlorine. For the next few years, your tap water can have either chloramines, chlorine, or both.

Chloramines are harder to remove from water than chlorine. Chlorine can be removed by letting water stand for 48 hours, or by boiling. However, these don't work for chloramines. Hence, some new tricks are needed. The simplest method you probably already have at hand is carbon filtration. Activated charcoal filters work, but they doesn't absorb as readily as chlorine, so you have to run the water through more slowly. A typical homebrew-sized filter can only take about a pint per minute, so you would have to start early to collect enough for your batch.

If you don't have patience with slow filtration, you can try chemical dechlorinators. Campden tablets, using sodium metabisulfate will do the trick. However, you have to be careful to not overdo it, since excess sulfite can stunt or kill your yeast. A quarter tablet per 5 gallon batch is needed. Ascorbic acid (vitamin C) will work too, and in smaller doses. You need about 4 ppm, or about 0.08 grams for a 5 gallon batch. This is what kidney dialysis systems in hospitals use. Ascorbic acid is probably a better bet, since a bit of extra won't kill yeast. It will bring down the pH of your brewing water, though the amount needed is so small it is unlikely to have much of an impact. If you have plenty of patience, note that chloramines is degraded by sunlight. A week in a carboy outside should do the trick. UV lamps work too.

The good news is that the presence of chloramines in your beer is far less deleterious than chlorine. Keep an eye on your yeast activity. As long as the yeast is doing OK, the chloramines levels is probably OK. Formation of chlorophenolics and other chlorinated byproducts are reduced by 98% with chloramines relative to chlorine. That means even if you do leave some of it in your brewing water, it won't be a significant problem.