HOW IS DRINKING WATER TESTED FOR SAFETY?

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 Testing Our Drinking Water


Photo: Miami-Dade Water and Sewer Dept.

What Kind of Tests are Run on Drinking Water?

Public water systems test drinking water for over 90 contaminants, running hundreds of analyses during the year. 

Process Control Testing

Water systems also conduct numerous process control tests that water plant operators use to monitor and adjust water treatment plant performance. Process control testing is performed on the incoming source water at at various stages of treatment.

Regulatory Testing

The U.S. EPA, Florida Department of Environmental Protection (FDEP), and Florida's Water Management Districts regulate which contaminants must be monitored, how often, and the maximum contaminant levels allowed. 

Most regulatory testing is performed on the finished water, after treatment and at the entry to the distribution system, with some testing performed in the distribution system. 

For instance, chlorine residual tests are conducted on the entry and out in the distribution system. A minimum level of chlorine must be present even at the farthest distance from the treatment plant.

Bacteriological tests are also conducted, sampled at both at the treatment plant and at multiple locations in the distribution system to ensure no contamination in the pipelines.

Sampling for tests to meet the lead and copper rule is done in homes, conducted by the homeowners at high risk locations (that may have lead plumbing services). Delivery and pickup of the sample containers and instructions are provided by the utility.

Regulatory testing standards include seven categories: 
  • Microorganisms
  • Disinfectants
  • Disinfection Byproducts
  • Inorganic Chemicals
  • Organic Chemicals
  • Radionuclides. 
These categories fall  under the National Primary Drinking Water Standards from EPA. FDEP requires all water treatment facilities to conduct these tests and report results regularly.

Utilities also conduct testing for the National Secondary Drinking Water Standards, which are cosmetic or aesthetic issues like taste and odor.

Every 5 years, EPA also requires testing for a list of contaminants that do not have any regulatory requirements yet. EPA uses these test results to determine if the contaminants should be regulated.

The Water Management Districts require testing on water sources, along with information on water withdrawals, water levels, and water demand from customers.

Here's a video highlighting the water quality laboratory for the City of Tallahassee:


Who Reviews the Test Results?

Water plant operators and managers review test results to make process adjustments and to verify the treatment levels are met. 

Utilities must also provide regulatory test results to FDEP (who then report them to EPA) and the Water Management Districts on a regular basis. 

Any test result that exceeds the drinking water standards mut be reported to FDEP immediately. If public health may be affected, the utility must notify the public with information and actions to take to prevent harm.

Who Conducts the Tests?

Process control testing is usually conducted at the treatment facility, as results are needed quickly to make adjustments to the treatment process. 

All regulatory analyses must be performed by a laboratory certified by the Florida Department of Health (FDOH) under the National Environmental Laboratory Accreditation Program (NELAP).

Testing for regulatory contaminants may be performed at:
  • On-site laboratories located at water treatment facilities,
  • Stand-alone laboratories owned by the utility,
  • Contract environmental laboratories, or
  • A combination.
Some process and regulatory analyses run continuously at the treatment facility, with sensors, online monitoring and recording. 

Larger utilities often have their own laboratories, either on -site at a treatment plant or at a stand-alone facility. 

Smaller facilities will typically perform some of the testing at a small on-site laboratory, but send most of the test samples to a contract environmental laboratory.

You can take a tour of JEA's Springfield Water Lab in Jacksonville. This is a stand-alone facility owned by the utility:



Here's a short video from Tampa Bay Water about their microbiology lab.

How Do We Know the Test Results are Right?

All laboratory analyses include strict requirements for Quality Assurance and Quality Control (QA/QC). These are methods used in laboratories to check accuracy and precision during testing. Some examples are running duplicate tests, spiking samples, checking results against certain standards. A robust QA/QC program is part of the NELAP laboratory certification process. 

In addition, the laboratories are inspected by FDEP and FDOH to ensure proper procedures are followed and record-keeping is thorough.

Career Possibilities in Water Laboratories

At a Florida Water Resources Conference, I volunteered as a mentor for a Mentor-Mentee Matchup. A few of the students who were majoring in Environmental Science were wondering how they could get a job in a laboratory. 

Applying at water utilities is a great idea for anyone studying the sciences. Many have their own laboratories and some have internship programs. The work is always interesting, always necessary, and a great way to earn money while serving the community.

Geek Out

Here's a training video from EPA: 

Do’s and Don’ts in Operating an NPDES Laboratory: Common Mistakes and Ways to Improve Results

Proper sampling is the first step towards accurate test results. 










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