City of Garland Press Release:

Water System Maintenance May Cause
Temporary Taste, Odor Change

The North Texas Municipal Water District (NTMWD) has scheduled a free chlorine maintenance that will be conducted on the NTMWD Wylie water transmission system and customers’ distribution systems for a 30 day period from February 19, 2010, to March 25, 2010. The City of Garland is a member of the NTMWD.
 
Consumers who are sensitive to taste and odor changes in drinking water might notice a change during this period. This process does not alter the quality of the drinking water provided to consumers. Your water is still safe to drink.
 
The Texas Commission on Environmental Quality (TCEQ) allows water suppliers to perform free chlorine maintenance. Free chlorine maintenance helps reduce the need for water suppliers to flush systems in order to maintain chloramine residual (required by the TCEQ) during the warm weather periods, thus conserving water. Free chlorine maintenance lasts about 30 days and is performed in cool weather months when water temperature is lower.
 
The NTMWD utilizes chloramines, a combination of chlorine and ammonia, in the water treatment process and to provide the disinfectant residual in the transmission and distribution systems as required by the TCEQ. Chloramines provide a longer lasting residual disinfection in water pipelines and storage facilities.
 
For more information about the North Texas Municipal Water District and the free chlorine maintenance process, visit www.ntmwd.com. For more information about the City of Garland Water Utilities, visit www.GarlandWater.com.
 

 
Contrary to what the title of this post might suggest, I don't have any idea how noticeable the change will be. For those that might notice, it's nice to have advance information.