• What is an EPTDS?
• Results of Water Quality Testing
• Distribution Zone Map

What is an EPTDS?

Ground water is moved from the wells to storage tanks in large diameter pipelines. The water is treated along the way. Treatment includes:

• Disinfection with sodium hypochlorite. Generated on-site from table salt and water, the product is like weak household bleach.
• Fluoridation with hydrofluorosilicic acid to prevent dental cavities. On most of the east side of the Rio Grande, the Water Authority adds fluoride. On the west side and in Distribution Zones 13 and 14, no fluoride is added. The water contains sufficient fluoride when it is pumped from the ground.

Treated surface water is pumped to certain storage tanks and blended with treated ground water. At the Entry Point to the Distribution System or the EPTDS, water from a storage tank enters the distribution system to deliver water to individual neighborhoods and customer taps by gravity flow. Specific EPTDS(s) provide water to each distribution zone. In some cases, treated water from an individual well enters the distribution system through a separate EPTDS. Water distributed within each distribution zone is of the same quality.

How Trunk Lines Work

From the valley to the heights, storage tanks are organized in trunks. Water moves in trunk lines that run from low to high ground, and down major streets. Pump stations move treated water from one storage tank to another.

Now, because of the San Juan-Chama Drinking Water Project, we have a system of north/south pipelines that connect all the trunk lines. They help distribute the treated surface water and water from low arsenic wells throughout the system, on both sides of the river. The result is a mix of treated waters from many wells and treated surface water in each storage tank.

Results of Water Quality Testing

The interactive map below is linked to tables that show the results of water quality testing. The Water Authority service area is outlined on the map. The blue lines on the map show the 20 distribution zones in the service area (including the new zone for the North West Service Area). Use the map to identify your distribution zone.

The table for each distribution zone gives a summary of water quality testing results for that zone and the average water quality testing results for the distribution system citywide. For each zone, there are two tables.

The first table shows the results of water quality testing to comply with drinking water quality regulations. Only the substances that were detected during compliance monitoring at EPTDS that feed a zone are listed in the table. The results for compliance monitoring for microbiological contaminants, disinfection by-products, and disinfectants measured throughout the distribution system are listed here. Substances that were not found in compliance monitoring are listed here.

The results of additional water quality testing for 2009 are summarized in the second table. These additional samples are collected to monitor the distribution system more frequently and for more substances than regulations require. Samples are collected in each distribution zone every three months.