When the Merchantville-Pennsauken Water Commission (MPWC) was first established in 1926, treating drinking water meant adding lime to control pH and chlorine to kill bacteria. Nearly a century later, the MPWC system has grown into a multi-stage treatment process designed to remove everything from naturally occurring minerals to synthetic industrial compounds. Here’s how that process works — and how it’s evolved.
The Foundation: pH Control and Disinfection
Believe it or not, the earliest treatment steps at MPWC remain in use today. Lime is still added into the water supply to raise pH, which reduces corrosion in distribution pipes and protects infrastructure. Chlorine disinfection, which was first used in a municipal system in the United States in Jersey City in 1908, continues to be a primary protectant against harmful bacteria and pathogens.
While these two steps form the backbone of the drinking treatment process, they address only a narrow range of groundwater concerns. As the science of water quality advanced, so did the number of treatments required to address new and emerging contaminants.
Removing VOCs through Air Stripping
In the 1980s, volatile organic compounds (VOCs) became widely recognized as a significant groundwater concern. MPWC responded by installing high-service pumps and air strippers at its treatment facilities. The air stripping process forces large volumes of air through impacted water, causing VOCs to evaporate and allowing them to be separated from the water system.
Greensand Filtration for Iron and Manganese Removal
At the start of the 21st century, the treatment process evolved again to address iron and manganese. Although they are naturally occurring minerals, groundwater sources commonly contain elevated levels. At excessive concentrations, the minerals can cause rust or discoloration, impact the taste of water and result in buildup or deposits in plumbing systems and pipes, damaging infrastructure.
In the early 2000s, MPWC installed greensand filters at three of its treatment facilities. Greensand, a natural mineral that is processed and coated with manganese dioxide, oxidizes soluble iron and manganese (as well as hydrogen sulfide) and converts them into insoluble – or solid – particles that can be filtered out of the water.
Targeting Unregulated Compounds with Carbon Filtration
With support from a New Jersey Department of Environmental Protection grant, MPWC installed carbon filters at one treatment site to address unregulated compounds – demonstrating that unregulated compounds could be removed, before standards and maximum contaminant levels had even been established. Activated carbon works through adsorption, meaning that contaminant molecules stick to the carbon surface, allowing them to be removed as the water passes through the filter.
This early step with advanced technology positioned MPWC well for what would become the biggest treatment challenge in decades.
Advanced Treatment for Emerging Contaminants
PFAS (per- and polyfluoroalkyl substances) and 1,4-dioxane are some of the newest and most complicated contaminants the water industry has faced. The manufactured, toxic “forever chemicals” break down slowly, pose adverse health risks and have been found in groundwater across the country.
The highly stable compounds are resistant to conventional treatment, and many water filters are incapable of removing them. As a result, water treatment now requires specialized treatment methods and rigorous testing to address PFAS and 1,4-dioxane.
MPWC’s response has been infrastructure-intensive. In 2018, construction was completed on a Granular Activated Carbon plant and Advanced Oxidation plant at the Woodbine facility. Similar treatment plants were incorporated at the National Highway facility, completed in 2023. Upgrades at MPWC’s remaining treatment sites are either underway or planned in the coming years to address evolving PFAS and 1,4-dioxane standards.
A Multi-Layer System
Today, MPWC’s treatment process includes a number of steps, each targeting a different type or class of compounds. And, the system has evolved as new science and advanced technologies become available. Daily water quality testing at each stage ensures the system is performing within required standards, from source to tap.
Over the last century, each treatment addition wasn’t a replacement — it was a new layer added on top of what came before. As new groundwater concerns are identified and regulations tighten, this layered approach will continue to define how MPWC protects the valuable drinking water for the communities it serves.
