Use the NSI proficiency testing (PT) studies to help improve quality and comply with regulations. There are no limits on the number of analysts or number of methods that you may report. Receive your final reports within 21 days of the study close date.

These environmental chemistry drinking water proficiency tests are designed for identification of target chemicals in drinking water.

If you have an immediate need for proficiency test results, PT Express™, our on-demand proficiency testing is available year-round. Call us at 1-800-234-7387 to place your order.

For determination of the following elements:
Alkalinity: 25 to 200 mg/L
Chloride: 20 to 160 mg/L
Conductivity: 130 to 1300 µmhos/cm
Fluoride: 1 to 8 mg/L
Nitrate as N: 3 to 10 mg/L
Nitrate/Nitrite to N: 3 to 10 mg/L
Potassium: 10 to 40 mg/L
Sulfate: 25 to 250 mg/L
Total Dissolved Solids: 100 to 1000 mg/L

Lead time specified is for studies that have already opened. The lead time for studies that have not yet opened will be applicable once the study opens. To view study numbers and corresponding study dates, please see the 2024 Proficiency Testing Study Schedule linked under the Resources section below.