Water supply: "Chlorine Burn-out"? How to proceed with water changes?
Hello, I noticed this notice (copied and pasted below, sorry its long, I just wanted to keep all the explanation together) on my city's water department web page.
I need to do a water change on my tank, which has plants and fish… but this notice is making me a bit wary. I mean, Prime should take care of the Chlorine right? I guess the part that has me worried is the Manganese and rust particles… doesn't seem like that would be good for my tank?
From October 1 – October 31, 2014, Water Supply Corporation will perform a routine chlorine burn out to the water system which will help prevent discoloration, odor and taste in the city’s water.
Every month, staff can be seen flushing fire hydrants to ensure the water we serve is safe and fresh. Water distribution staff is tasked to ensure that water in all points of the system is acceptable to our customers.
There are times that the water is discolored to a yellow, orange or even brownish color. This discoloration is caused by cast iron or steel water mains and private plumbing and at times manganese. Manganese is naturally present in water sources but can increase in years of heavy rains on the watershed. Manganese is not harmful at the levels found but can be a nuisance by discoloring the water. Over time, manganese will attach itself to the pipes andrelease when there are extreme changes in the velocity or pressure similar to when there is a main break or during an annual fire department testing of the hydrants. Nitrification can also occur in water systems that use chloramine for their residual disinfectant. Nitrification is a microbial process that converts ammonia and similar nitrogen compounds into nitrite (NO2–) and then nitrate (NO3–). The key to stopping nitrification is to starve the nitrifying bacteria of nitrogen. WSC is currently experiencing this problem in some of their areas and
will be performing a chlorine burn out on their entire water system to treat the problem.
Remedy: Normally the water is treated with a disinfectant called "chloramine" which is a long-lasting disinfectant that ensures the safety of the water. The "burn out" is a change in the treatment process from chloramines to free chlorine. WSC will perform a free chlorine shock October 1 – 31, 2014.
There will be extensive directional flushing of the system during this time. This process should help remove iron, manganese and other constituents in the mains; provide a key component to stop nitrification; and improve water quality with no associated health risks. Free chlorine is the disinfectant of choice when performing a system-wide maintenance flush. It will help
clean the lines, stop nitrification and ensure that the water continues to be safe to drink.
Potential inconveniences: During these efforts to improve water quality as a whole, there will be times of lower water pressure, odors and taste that are abnormal. Possible particles seen in the water should be rust particles from the iron mains with manganese attached. Each water system will attempt to flush the particles,color and odor from the mains with directional flushing.