The city of San Diego has an inconsistent record when it comes to water safety, although great strides have been made in recent years. As recently as a few years ago, San Diego ranked among the worst tap water cities in the country.
Poor infrastructure was the primary issue affecting the tap water in San Diego. Damaged water pipes, lead and copper contamination from older pipes, and chemicals leaching into the system have plagued the water system. However, San Diego has made a concerted effort to address these outstanding issues, and The water quality is now legally compliant with the Safe Drinking Water Act.
San Diego Water Quality Report: What is in the Water?
| Contaminant | San Diego levels | EPA action limit | EPA's public health goal |
|---|---|---|---|
| Lead | 5 ppb | 15 ppb | Zero |
| Total trihalomethanes | 1.5 to 79 ppb | 80 ppb | Zero |
| Hexavalent Chromium | 0.02 to 0.22 ppb | 100 ppb | 0.02 ppb |
| Bromate | 0 to 9 ppb | 10 ppb | Zero |
| Total haloacetic acids | 0 to 19 ppb | 60 ppb | Zero |
In January 2020, San Diego announced a major, city-wide initiative to use drones to inspect and replace all old pipes by 2024. The work continues through 2023, although the latest water quality report showed that the lead problem in the city's tap water still persists.
The average lead level of San Diego's water (5 parts per billion) falls below the lead action limit set by the Environmental Protection Agency (EPA) under the National Primary Drinking Water Regulations (NPDWRs). However, the agency also establishes that lead in drinking water isn’t safe even in trace amounts.
We strongly recommend that San Diego citizens regularly test their water for lead (at least twice a year). If the test shows any lead presence, then the solution is to purchase a water filter for lead removal to filter out the lead in your water.
In addition to lead, the report also shows the presence of hexavalent chromium, also known as chromium VI (averaging 0.06 ppb with a maximum level of 0.22 ppb). The EPA’s action limit for total chromium (meaning all kinds of chromium variations) is 100 ppb, but it sets the public health goal for hexavalent chromium at 0.02 ppb.
Since the San Diego Chromium 6 levels are higher than the safety limit set by the EPA, you should consider purchasing a chromium 6 water filter to remove the chromium 6 in your water.
Lastly, the city’s water has disinfection byproducts such as bromate (up to 9 ppb), total trihalomethanes (up to 79 ppb), and haloacetic acids (up to 19 ppb). Since the NPDWRs associates these impurities with an increased risk of cancer, the EPA sets a public health goal of 0 ppb for all 3 by-products.
Is The Water Hard or Soft?
San Diego water is considered very hard, with over 180 PPM of minerals in a water sample. This puts it in the highest grade for water hardness.
San Diego Water Sources
San Diego gets most of its water from the San Diego County Water Authority. The San Diego County Water Authority receives water from the Colorado River and the State Water Project. The water provided through those sources is raw water.
Both water sources are subject to drought, geology, and land activities. San Diego monitors both sources and adjusts its ratio from each accordingly. By doing this, the city can ensure that drinking water will be safe once treated at the San Diego Water Treatment plant.
The city also gets less than 10% of its water from treated sources. The treatment plants include the Skinner Water Treatment Plant, Twin Oaks Valley Water Treatment Plant, and the Carlsbad Desalination Plant.
How Tap Water is Treated in San Diego
The city’s Public Utilities Department takes a tiered approach to treat the water that enters the San Diego water treatment plant with the following steps:
Watershed Protection
San Diego closely monitors any sources of water or water storage points. The monitoring includes strictly enforcing swimming, boating, and dumping regulations.
Coagulation
Chemical components get mixed into the water entering the water treatment plant. Many particles are negatively charged, causing them to repel each other. Coagulation changes the particles from negative to neutral.
Flocculation
Coagulated water gets mixed and makes neutral particles in the water collide. These particles clump upon impact, creating a “floc.”
Sedimentation
Once mixed, the water flows through sedimentation basins. Because the floc is heavier than the water, it drops into the basins, taking particles of contaminants with it. The clean water gets skimmed off the top of the sedimentation basins.
Primary Disinfection
The collected water is then disinfected. The method depends on the plant the water flows through on its way to the tap water system.
The Alvarado and Miramar water treatment facilities use ozone to disinfect water. The Otay facility uses chlorine dioxide. Both processes disinfect the water and improve its taste.
Filtration
After disinfection, the water flows through deep filtration beds. Even the smallest contaminant particles get picked up as the water works through the beds. The result is pure water.
Secondary Disinfection
Chlorine and ammonia get added to the water after the filtration process. The added chemicals merging produces chloramines, which fight microbial contamination. The water is also adjusted accordingly to maintain a healthy pH level.
The result of going through that process is thoroughly clean, highly drinkable water that gets distributed throughout the San Diego area.
Do They Have the Cleanest Tap Water?
No, but San Diego is working hard to improve their already safe water. San Diego had and has much to overcome because of an aging water system. It has made great strides through infrastructure improvements to enhance its water quality.
