Water Quality

Water system to temporarily change method of disinfecting drinking supply

The City of San Angelo’s Water Utilities Department will change how it disinfects the public water supply from June 1-30.

The Water Department normally uses chloramine, a mix of ammonia and chlorine, to disinfect water. In June, the Water Department will use only chlorine, also known as “free chlorine.” The yearly temporary conversion from chloramines to free chlorine – a common practice for municipal water systems – ensures water safety in pipelines by ridding mains of residual microscopic organic particles. That yields the highest quality of drinking water.

Citizens may see more flushing of fire hydrants in June. Water lines with low flow must be flushed more often to keep free chlorinated water moving through the system. 

Free chlorine is a stronger disinfectant than chloramine. Water users may note a slight change in the smell, taste and look of their water. This may include a “chlorine odor” and slight discoloration. Most symptoms should lessen after a couple of weeks; they do not affect the safety of the water. 

The Water Utilities Department encourages kidney dialysis patients to talk with their equipment supplier; different equipment may have varying needs and require adjustments. The City has contacted local hospitals to alert them of the change.

Some reverse osmosis systems are not designed to work with water that has free chlorine. Owners of RO systems should check their operation manuals or system manufacturers to ensure they will not be adversely affected by the change.

The process most fish tanks have for removing chloramines from water should do the same with free chlorine and need no adjustments. Fish tank operators should confirm that with their equipment supplier. Pet stores have also been told of the conversion. 

The Water Department will monitor chlorine levels and water-quality standards in the distribution system on a daily basis to ensure all regulatory standards are met.

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Water system's temporary conversion to free chlorine

The City of San Angelo’s Water Utilities Department will change the disinfectant used in the public water system from chloramine to free chlorine beginning June 1 for approximately four weeks. 

Why is our water system making these changes to our disinfection process? Our water system normally uses ammonia and chlorine as the main means to disinfect water.  Mixing these two chemicals forms chloramine, the most common disinfectant used in the United States for water systems that use lakes and rivers as their source. Occasionally, these systems must return to free chlorine as their disinfectant for a brief time to properly maintain the distribution system. Free chlorine works better than chloramine to control thin biofilms of organics and microbes that can build up in pipelines over time. This is common preventive maintenance used by most water systems that use chloramine as their main disinfectant.

When will this start and how long will it last? The conversion will start June 1 and last approximately four weeks. 

Will I need to do anything differently during this change? No action is necessary.  You may drink and use your water normally.

What changes to the water quality will I notice during this period? Initially, you may notice more of a chlorine taste and smell to your water, especially in showers and sinks. Water also may also be slightly discolored in areas with low flows in water mains. These symptoms should lessen after a couple of weeks but may be present (though less noticeable) during the four-week span.

I have a fish tank. How will it affect my fish? We recommend you check with your equipment supplier. The process you have in place to remove chloramines in the water should also remove free chlorine. No change or adjustment should be needed. 

I’ve heard this can affect kidney dialysis machines. Is this true? We recommend you check with your equipment supplier. Different equipment may have different needs or adjustments.   

Will the City do anything to lessen the taste and odors we might experience during this change? Yes, the City will implement procedures to reduce effects as much as possible. However, changes will likely occur and may persist. We will monitor free chlorine levels throughout the system each day to ensure they are at correct levels. You may also see more flushing of fire hydrants. Water lines with low flow must be flushed more often to keep free chlorinated water moving through the system. The Water Utilities Department does not like doing this during drought restrictions, but in some areas it will be required.  

Is there a possibility of free chlorine bleaching my clothes? Free chlorine is a stronger disinfectant than chloramine. Even though it may have more of a chlorine smell, the disinfectant residuals in the system will actually be lower than they are currently. We don’t expect problems with bleaching of clothes. If you have brand-new clothes that have never been washed, you might wash them first in cold water to let their colors “set” before using a hot water wash.

Will this process improve the quality of my water once it is completed in four weeks? Typically, after a change to free chlorine and then back to chloramine, less disinfectant is needed to maintain residuals in the distribution system. So, if you are sensitive to the taste and smell of chloramine, you should see an improvement in water quality after the conversion. 

Is there a way to reduce or remove the chlorine taste and smell during this period? Yes. A carbon filter is effective at removing free chlorine taste and smell, as well as chloramines. If you have an existing carbon filter on your faucet, reverse-osmosis system or cartridge under the sink, these should remove any additional taste and odor during this period. These are available at local retail stores. Some are inexpensive and easy to install. 

Does the taste and odor from chlorine affect everyone the same? No. The taste and smell of chlorine in drinking water does not affect some people at all. Others with a higher sensitivity to smells could be affected. Free chlorine can give water a “swimming pool” smell. 

Whom can I contact with additional questions or concerns? Please call the Water Utilities Department at 325-657-4300 for more information.

The Water Quality division's mission is to analyze and evaluate the quality of the source water, treated water and wastewater for compliance with state-mandated water quality standards. 

This mission is accomplished through the cooperation of various City operations, including the water treatment plant, the wastewater treatment plant, and the Water and Wastewater Collections and Distribution divisions.

The Water Quality Division was formed in 1997 after the consolidation of three separate City laboratories, including the water treatment plant laboratory, the wastewater treatment plant laboratory, and the City/County Health Department laboratory. Consolidation of these three labs provided for more efficient analyses, as well as better cross-training for laboratory personnel. The laboratory was awarded NELAC Accreditation for bacteriology in 2008.

Information and resources

• Water chemistry explained
• Coliform bacteria information
• Household water treatment alternatives
• Conventional municipal water treatment methods

Current drought level

San Angelo is in standard conservation, which restricts outside watering to twice every seven days at no more than 1 inch per week. Watering is prohibited between noon and 6 P.M, and runoff of more than 150 feet down any street, gutter, alley or ditch is also prohibited.

Report watering violations by clicking on this link or calling 325-657-4409. Do your part; be water smart!