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Water Quality in San Jose, California: What You Need to Know

Overview

San Jose, located in the heart of Silicon Valley, relies on a mix of local and imported water sources to meet the needs of its growing population. While the water supplied by the San Jose Water Company generally meets federal and state drinking water standards, concerns remain about the presence of contaminants and the long-term health effects of continued exposure.

What's in Our Water?

Even though the water in San Jose is treated and considered safe by regulatory standards, trace levels of various chemicals, minerals, and contaminants can still be found in the supply. These may include:

Chemicals and Contaminants Detected

  • Chlorine – Used as a disinfectant, but it can create harmful byproducts like trihalomethanes (THMs) and haloacetic acids (HAAs).

  • Fluoride – Added to prevent tooth decay, but controversial for potential links to neurological and endocrine issues.

  • Nitrates – From agricultural runoff; high levels can pose health risks, especially for infants.

  • Lead – Typically comes from older household plumbing; even small amounts can affect brain development.

  • Chromium-6 – A known carcinogen found in some local groundwater sources.

  • Per- and Polyfluoroalkyl Substances (PFAS) – "Forever chemicals" linked to cancer and hormone disruption.

  • Arsenic – A naturally occurring element in some groundwater sources, linked to cancer and skin lesions.

Minerals in the Water

  • Calcium & Magnesium – These contribute to "hard water," which can lead to scale buildup in pipes and appliances.

  • Sodium – Occurs naturally but can be problematic for people on sodium-restricted diets.

  • Iron & Manganese – May stain laundry and fixtures and affect taste and odor.

Where Our Water Comes From

San Jose's drinking water is sourced from:

  • Local groundwater basins

  • Imported water from the Sacramento-San Joaquin Delta

  • Surface water from the Santa Clara Valley Water District

Each source has unique qualities and potential for different contaminants, especially as drought, agriculture, and industrial runoff impact water purity.

Showering: The #1 Way We Use Water

You might be surprised to learn that the average San Jose resident uses more water in the shower than anywhere else in the home. In fact, showers account for nearly 30% of indoor water use.

Why is this important? During a hot shower, your skin and lungs can absorb volatile chemicals like chlorine and chloroform more easily through inhalation and dermal absorption than through drinking alone. This makes water filtration for showers just as important as filtration for drinking water.

The Importance of Water Filtration

Investing in a reliable water filtration system can help reduce your exposure to harmful substances. Here are a few options to consider:

  • Activated Carbon Filters: Great for removing chlorine, THMs, and some VOCs.

  • Reverse Osmosis Systems: Highly effective at removing heavy metals, fluoride, nitrates, and PFAS.

  • Whole-Home Filtration Systems: Ideal for treating both drinking and bathing water throughout your home.

  • Shower Filters: Reduce chlorine and improve air quality during bathing.

What You Can Do

  • Check your water quality: Use tools like EWG’s Tap Water Database to find recent test results for your zip code.

  • Install filters: Choose certified systems that match your needs.

  • Conserve water: Shorter showers and efficient appliances help reduce usage and minimize contamination risk.

  • Advocate for policy change: Support stricter water quality standards and infrastructure improvements in your community.

Conclusion

San Jose’s water is treated and monitored, but that doesn’t mean it's free from risks. Understanding what’s in your water—and how to reduce your exposure—can protect your health and improve your quality of life. Filtration, awareness, and conservation are key steps to ensuring a cleaner, safer water future for all.

 

Get a Free In-Home Water Quality Test – Discover What’s in Your Water with Dialed In Plumbing.

Contact us below and mention free in home water quality test to receive a 5% discount on a water filtration system.