Conversion Back to Chloramines in Drinking Water Supply

Temescal Valley Customers Drinking Water Notice and FAQs

Last April, EVMWD notified customers of a temporary change from a chloramines disinfection process to a chlorine disinfection process for its water supply.

Beginning September 3, 2019, EVMWD will switch back to a chloramines disinfection process. Both chemicals are safe and effective methods of water disinfection approved by the Environmental Protection Agency and the California Department of Public Health (CDPH). The chloramination process is accomplished by treating water with a compound of ammonia and chlorine, as opposed to the current and temporary procedure that uses only chlorine. This upgrade may require changes on behalf of some of our customers.

Precautions must continue to be taken by customers to remove or neutralize chloramines and free chlorine during the kidney dialysis process, in the preparation of water for fish tanks and ponds, and for businesses requiring highly processed water.

Customers may notice EVMWD staff flushing fire hydrants throughout the Temescal region and may notice intermittent and temporary changes in taste, odor and color of their tap water during the conversion period. The free chlorine conversion process  should take two to five days to fully establish.

For any questions or concerns please contact EVMWD at (951) 674-3146 or by email at:


1. What are chloramines?
Chloramines are disinfectants used in drinking water to keep water safe from bacterial and virus contamination.

2. Why is EVMWD switching from chlorine to chloramines for disinfection?

There are several advantages to using chloramines. The most important one is the improvement in the taste and odor of the water. Chloraminated water has much less objectionable taste and odor than chlorinated water. Water treated with chloramines will form less disinfection by-products, such as trihalomethanes, which are suspected carcinogens. Chloramine has the ability to sustain itself in the water longer than chlorine, thus providing consistent bacterial control.

3. Will home water treatment units remove chloramines?
Removal of chloramines by home water treatment units will depend on the unit design. In-home water filtration units do not remove chloramines completely. In any case, removal of chloramines may not be necessary, since they are safe for the general population to consume. For information regarding your specific equipment, you should consult the manufacturer. 

4. What are the effects of chloramines on swimming pools?
Chloramines have little to no effect on pools. For questions related to chloramines and your pool, you may contact a pool service professional.

5. Chloramine disinfection method is safer and will produce better tasting water, but may affect the following:
• Kidney dialysis patients: seek advice from your doctor
• Aquatic creatures: check with your local pet store
• Medical laboratories

6. Why are free chlorine and chloramines harmful for dialysis patients?
Both free chlorine and chloramines may harm kidney dialysis patients during the dialysis process if it is
not removed from water before passing into the bloodstream. Like everyone else, dialysis patients may drink water treated with either free chlorine or chloramines because the digestive process neutralizes the chemicals before they enter the bloodstream.

7. What are the benefits of chloramine water treatment?
• Improved water taste and odor
• More residual in distributions system to continue disinfecting longer
• Lower disinfection by-products

8. What does “hydrant flushing” mean?
EVMWD personnel will strategically draw the chlorinated water through selected fire hydrants located all around the service area for several days.  Hydrant flushing also helps to wash out sediments that have collected in water mains throughout the distribution system.  

9. Will I see a drop in water pressure due to the flushing?

Most customers will not see a drop in water pressure. If a change in pressure does occur, it usually lasts
for less than half an hour. If you experience a significant loss of water pressure lasting longer than 30
minutes, please contact EVMWD at (951) 674-3146 or by email at:

10. Will hydrant flushing in my area cause cloudiness or sediment in my water?
Since the flushing process can stir up sediments in water mains, you may notice occasional short-term
Cloudiness, brown/yellow color in your water. If your tap water is cloudy or colored, open your faucet and allow water to flow until the clarity improves. If your tap water remains cloudy for an extended period of time, please contact the EVMWD  at (951) 674-3146 or by email at:

11. Where can I get more information?
For answers to any questions related to your water quality, please contact EVMWD (951) 674-3146 or by email at: