The science of safe water

When you turn on your tap, you may not always think about the science happening behind the scenes to ensure your municipal water is safe. But at the York-Durham Regional Environmental Laboratory (REL), a dedicated team provides a range of analytical services for municipal drinking water and wastewater (sewage), and industrial monitoring programs.

Jointly owned and operated by York and Durham Regions, this state-of-the-art facility is accredited by the Canadian Association for Laboratory Accreditation (CALA) to ISO/IEC 17025 and licensed by the Ministry of the Environment, Conservation and Parks.

Charu Aggarwal, a Laboratory Technician in the Organics Department of the REL, gives an in-depth look at the important work being done there.

Why water testing matters

Laboratory testing plays a fundamental role in protecting public health, maintaining water quality and supporting responsible wastewater management.

For Charu, the work is about much more than running samples through machines.

"The testing done at the lab serves as an important scientific link between water treatment operations, environmental protection and the communities we serve," says Charu.

For municipal drinking water, the testing is an essential part of a much larger monitoring system. Water is examined throughout the treatment process and distribution system. The REL analyzes samples to help verify that drinking water meets applicable provincial standards. And it provides valuable information to the teams responsible for maintaining our water systems.

Wastewater testing is equally as important. Wastewater contains a complex mixture of substances from homes, business and industries. By analyzing samples collected at different stages of treatment, operators can assess how effectively pollutants are being removed and whether adjustments to the treatment processes may be necessary.

The work also extends beyond drinking water and wastewater treatment plants. Environmental samples such as groundwater, surface water, stormwater and industrial wastewater are also analyzed. This supports environmental monitoring programs and helps identify potential sources of contamination.

"A clear drinking water sample, a groundwater sample and a treated wastewater sample all require different analytical approaches," Charu explains.

The journey of a water sample

What happens after a sample arrives at the lab? The process begins before any testing takes place.

First, the Lab Administration team reviews the sample and its accompanying documentation. This step is critical because chemical and biological characteristics can change after collection if samples aren't handled properly.

Each sample is then entered into the laboratory's information management system and assigned a unique identifier that allows it to be tracked from arrival to final reporting. After this step, samples are placed in the walk-in fridge to maintain storage conditions before analysis begins.

From there, analysts ensure testing is conducted within the acceptable hold time. Some samples require preparation for testing, such as extraction or preservation treatments, while others can be moved directly into specialized analytical instruments.

The testing itself is only part of the process. Quality control checks, data reviews and verification steps are performed throughout the process to ensure results meet rigorous standards before they are released.

“Every step is important because the people using our results need to be able to trust the information we are providing,” says Charu.

Meet the experts behind the results

Behind every result is a team of highly skilled lab professionals from various scientific backgrounds, including chemistry, microbiology and environmental science.

“One of the things that I appreciate most about working at the REL is the diversity and knowledge within our team,” says Charu. “Each department has its own specialized skills, but all of our work is interconnected.”

The inorganic chemistry analysts use a variety of chemical and instrumental methods to measure parameters such as nutrients, solids and other chemical characteristics of water and wastewater. The organic chemistry analysts, including Charu, work with specialized equipment to identify and quantify organic compounds often at trace concentrations. The microbiology analysts specialize in detecting and measuring micro-organisms that can indicate potential contamination.

The laboratory also relies on a dedicated Lab Administration team to receive, track and document every sample that comes through the facility; and the Laboratory Information Management System (LIMS) and Technology team to manage the data and ensure results are delivered to clients and regulatory programs.

More than just a machine

One of the biggest misconceptions about laboratory testing is that samples simply get placed into a machine and a result appears. In reality, the process is much more complex.

"I think what might surprise residents is how much testing happens behind the scenes and how sensitive our equipment really is," says Charu.

Some instruments can detect contaminants at concentrations as small as parts per billion, which is roughly equivalent to finding a single drop of water in a large backyard swimming pool.

Most residents will never see what goes into monitoring water and wastewater systems, But every day, the REL’s team is working behind the scenes to monitor water quality and support environmental protection across York and Durham Regions.

For more information on how the Region of Durham treats and distributes safe drinking water, visit durham.ca/water.