Water Quality Concerns

Taste & Odors
DocumentMany customer complaints involve taste and odor issues, but these issues are some of the most difficult for a water system to address. One reason for the difficulty is that taste and odor evaluations are totally subjective: what is offensive to one individual may not be even detectable to another.

All water has its own unique taste and odor characteristics. DeSoto purchases all of its water from Dallas. Like many other water suppliers, we occasionally experience taste and odor changes. In the summer and early fall, algae in area lakes occasionally give water an earthy taste and odor.

Temperature change and excessive rain can also alter taste. These changes do not affect the safety of the water, and for the most part, can be corrected by flushing fire hydrants in the water system. 
During the treatment process, chlorine is added to water as a disinfectant. Before the water leaves the treatment plant, ammonia is added to form chloramines to keep the water disinfected while it is distributed to homes and businesses. Chloramines may impart a chlorinous, or medicinal, taste or odor to your drinking water. Chloramines, rather than chlorine, are used to maintain a disinfectant residual because they are more stable, form fewer disinfection by-products, and tend to produce less offensive tastes and odors. 
An earthy or musty smell, particularly in hot water, may be the result of an algal bloom in the untreated water supply. Algae thrive at different times of the year in reservoirs. Taste and odor producing algae typically bloom in the late summer or fall. Although algae are removed during the treatment process, some of their metabolites may be left behind.

The two most common metabolites are geosmin and 2-methylisoborneol (MIB). Even though these compounds are harmless, the human senses of taste and smell are extremely sensitive to them and can detect them in the water at concentrations as low as 5 parts per trillion. 
A rotten egg smell typically occurs from a lack of oxygen in the natural or man-made reservoir storing water before it is treated. It is caused by bacterial decomposition of algae and organisms, which, when no oxygen is present, produces hydrogen sulfide. Hydrogen sulfide emits a rotten egg smell. The district’s treatment process oxygenates the water and removes the rotten egg odor. Although unlikely, some residual odor may remain.

When the naturally formed scale on the interior of the piping system is disturbed, and when turbulence with the water happens, some water discoloration may occur for several hours. The white discoloration of water usually means air is entrapped in the water. Running your faucets for a minute or two can usually eliminate white discoloration.

Other discoloration may require a different approach. During this time, limit your water usage, especially hot water. This will limit the storage of discolored water in your water heater and help prevent fixtures, clothing, and dishes from staining.

If discoloration continues for an extended period of time, please notify the City of DeSoto Water / Wastewater Department.

Other common odors you may occasionally notice in your tap water are fishy, grassy or marshy odors. These are also caused by compounds produced by different types of algae. Although these compounds may impart an odor, they do not adversely affect the safety of your drinking water.

Stains, Rings, Discoloration, And Mineral Deposits
Municipally treated water has been disinfected with harsh chemicals in order to comply with local, state, and federal standards. The issues of stains, rings, or discoloration are issues that develop AFTER the water comes into the home and is used or left to sit. Once chlorinated water is exposed to the air, the chlorine dissipates to a gas. The water in your plumbing system is in a closed loop and is not exposed to any issues until after it exits your plumbing fixtures or appliances.

The Water Maintenance division receives numerous calls from residents regarding stains, rings, discoloration, and mineral deposits in their toilets, showers, and sinks. The guide below will help you to understand the root cause of these and how to treat them. This guide is to simply identify the aesthetic problem, what causes the issue, how to take care of it and possibly prevent its return. It is easy to assume there may be a problem with your water, however most issues are NOT water quality related.