Water Quality

The City of Issaquah is committed to delivering the best quality drinking water. To that end, we remain vigilant in meeting the challenges of source water protection, water conservation and community education while continuing to serve the needs of all of our water users.

Water Quality Reports

Each year, we take hundreds of water samples to determine the presence of any radioactive, biological, inorganic, volatile organic or synthetic organic contaminants. Our annual Water Quality Reports illustrate the results of those tests, as well as other valuable information.

Most Recent Water Quality Report

All Available Water Quality Reports

Updates

UCMR3

This information has been updated to reflect most recent data and better describe how our water is blended.

PFC Test Results: Lower Issaquah Valley Aquifer

Substance
 (units of measurement)
 Well 4  (2013)  Well 4 (2014)1Well 4  (2015) At the Tap   Maximum Level (November 2015) At the Tap  Maximum Level  (February 2016)2 EPA
 Provisional 
 Health
 Advisory (issued 2009) 
 
 At the
 Tap
 Maximum
 Level (May 2016)
3  
At the Tap Maximum Level (June 2016)4 
EPA Lifetime Health Advisory (issued May 2016)5
PFBS (ppb)NDND0.0695NDNDNoneNDNDNone
PFHpA (ppb)
0.02580.0234
0.02070.00531NDNoneND
NDNone
PFHxS (ppb)
0.2410.201
0.1940.04730.0375None
ND
NDNone
PFNA (ppb)
0.02800.0266
0.0221NDNDNone
ND
NDNone
PFOA (ppb)0.02150.0200
0.0181NDND0.4
ND
ND0.07
PFOS (ppb)0.6000.514
0.4720.1060.07720.2
ND
ND0.07
ND — not detected


For the test results taken "At Well 4," this water was then blended with at least one other well before it was distributed. For more information, view our PFCs webpage.

After publication of its 2014 Water Quality Report, the City of Issaquah received the following corrected information from the testing lab.

This test was conducted after the City reduced the amount of water pumped from Well 4.

3 This test was conducted after the City stopped pumping from Well 4 in the winter of 2016.

This test was conducted after the City started to use a filtration device on Well 4.

5 Advisory is combined PFOA and PFOS levels.

Radium

While 2009 test results for combined radium (pCi/L) — which found no violation — were included in the City's 2009 Water Quality Report, the same results were inadvertently not included in the 2010 Water Quality Report. Subsequent samplings in May and October of 2012 found no level of combined radium.