Skip To Main Content

Water Quality Testing

Washington state law (RCW 28A.210.410 and RCW 43.70.830) requires drinking water in all K–12 public schools built before 2016 be tested for lead at least once between July 1, 2014, and June 30, 2026.

The purpose of lead testing is to identify drinking water outlets that are potential sources of lead exposure. It is natural for lead to accumulate in older or infrequently used drinking water outlets. These outlets are identified through testing so they can be shut off or replaced to reduce exposure to lead from school drinking water. 

MISD has conducted lead testing previously in 2016, 2017, 2019 and 2021. As part of continuing to provide safe and healthy learning environments for students and staff we partnered with the Department of Health (DOH) in October of 2025 to test our schools' drinking water.

What We’ve Learned 

In October of 2025​, 305 drinking/cooking water outlets across 5 of our 6 schools were tested. Water from outlets used for drinking or food preparation were tested for lead by a state-accredited laboratory. Tests were not conducted at Northwood or the new building at Islander Middle School as they were built after 2016.

Test results returned on November 21, 2025, showed ​24​ water outlets across five schools with elevated lead levels. Per RCW 28A.210.410, elevated lead level means a lead concentration in drinking water that exceeds five (5) parts per billion (ppb). 

What We’re Doing 

  • Upon receiving test results on November 21, 2025, any outlet exceeding 15 ppb was shut off immediately.
  • All affected fixtures were replaced with new, compliant fixtures, which are permanent solutions. All fixtures were replaced by the end of December 2025.
  • We have worked closely with the DOH to develop a remediation plan to reduce lead levels in drinking water.
  • Fixtures with elevated lead levels were re-tested on April 29, 2026. Results were received on May 21, 2026 for all schools except Lakeridge Elementary, whose results were received on May 29, 2026, due to a backlog of test reviews at DOH. All re-tested fixtures passed except for one location at Lakeridge Elementary. This fixture has been taken out of service and will undergo additional remediation. Once remediation is complete and follow-up testing confirms acceptable lead levels, the testing results spreadsheet linked below will be updated and our community will be notified.
  • View October 2025 Test Results, April 2026 Re-Test Results, and Mitigation Measures

Why Lead is a Concern 

Children are exposed to lead from a variety of environmental sources. Each exposure contributes to the amount of lead in a child’s body. Some common exposure sources include: 

  • Dust from old, deteriorating lead paint.  
  • Contaminated soil. 
  • Lead dust tracked into the home from external sources, such as parents and regular visitors who work in certain industries where lead is present. 

While the likelihood of school drinking water alone causing an elevated blood lead level is very low, it is important to reduce exposure from every source as much as possible. Children six years old and younger are the most susceptible to the effects of lead. Their growing bodies absorb more lead than adults, and their brains and nervous systems are more sensitive to the damaging effects of lead. Even at very low levels of exposure, children may experience effects, such as lower IQ levels, reduced attention span, hyperactivity, poor classroom performance, or other harmful physical and behavioral effects. Children over the age of eight are less susceptible to the impacts of lead exposure. Children who have been exposed to lead may not look or act sick. The best way to tell if a child has been exposed is with a blood lead test. 

Where to Learn More 

For more information about water quality in our schools, please contact ​Kathy Zurawski​ at ​kathy.zurawski@mercerislandschools.org OR 206-230-6186​. Additional information about lead exposure, as well as how to prevent lead exposure, is available at doh.wa.gov/lead. You can also reach out to the DOH Childhood Blood Lead Program at 800-909-9898 or lead@doh.wa.gov for more information. If you are concerned that your child has been exposed to lead for any reason, ask your healthcare provider about having them tested for lead. 

Closing Note

The Mercer Island School District is taking thoughtful, thorough steps to ensure that all drinking water in our schools is safe. Through proactive testing, immediate action, and long-term improvements, we are committed to maintaining a healthy environment for every student and staff member.