July 1, 2020

The Future of our Water Supply

Custom Design of Cross-Connection System for Water Supply Protection

An Air Gap Break Tank System for the cities of Durham and Cary, NC.

Local municipalities and water authorities have a responsibility to their local community to guarantee that the freshwater supply needed to meet daily demands is always available. But substantial population growth and unintentional overuse have created a different reality, the supply of potable water may not be enough to meet future needs.

In general, the freshwater supply is limited to approximately 1% of the total water supply on Earth. Water replenishes itself through the natural water cycle, but unexpected dry periods can further strain the freshwater supply. Protecting this natural resource is not only vital for the environment, but it is also essential for the communities we serve.

To help ward off the possibility of not enough water, conscious efforts to conserve freshwater can be seen everywhere. Whether it is by encouraging residents to use rain barrels to capture and repurpose rainwater drainage or setting local guidelines on residential lawn watering, these seemingly small actions add up to make a real impact.

Municipalities have also found they can further succeed with water conservation efforts by implementing recycled, also referred to as reclaimed, water systems. While these systems are intended to benefit the environment, they have been shown to make a positive impact on a social and economic level as well.

Reclaimed water practices, a way of repurposing wastewater, dates back to the Bronze Age (ca. 3200 – 1100 BC) when civilizations reused domestic wastewater for irrigation and aquaculture needs. While the practice declined in the 1800s due to concerns about sanitation, it regained popularity in the twentieth century. Advances in technology and science offered reassurance that properly treated wastewater can safely be used for a wide variety of applications, like agriculture irrigation, commercial or industrial uses.

Water reclamation has even gained popularity at a national level with the United States Environmental Protection Agency’s February 2020 release of the National Water Reuse Plan (WRAP). Developed with input from water leaders at the federal, state, and local level, WRAP is a collaborative plan that entails 37 actions that water partners can take to help establish freshwater security.

And while protecting the water supply is the primary goal of water reclamation, ensuring the safety of the community is a guiding principle whenever implementing these systems. Reclaimed water processes need to ensure potable water systems are not contaminated from inadvertent cross-connection or backflow of reclaimed water.

Mitigating the risk of cross-contamination of potable and non-potable resources have been in place for decades. In 1973, the EPA released the Cross-Connection Control Manual, which has been the go-to educational and technical-reference tool for everyone involved in water management, whether it be a health official or a plumber.

It is with these guidelines, along with the field knowledge from experts in the water movement and management industries that water reclamation can be done effectively, efficiently, and safely. Metropolitan Industries’ experience with water movement applications means we understand the unique needs associated with the delivery of both potable and non-potable water. Our team of engineers, designers, and application specialists are well-versed in creating solutions that help meet the intended goals of a community looking to implement water reclamation.

Most recently, we partnered on a water reclamation project for the cities of Durham and Cary, North Carolina.

The cities were looking to reduce the maximum daily need of potable water in effort to increase the reliability of the cities’ drinking water supply, while also buying more time before needing to expand the physical space of the treatment facility.

The cities were equipped to deliver potable water through their water mains throughout the town and had separate mains to distribute non-potable water for alternate uses, such as toilet flushing, cooling tower recharge, and turf irrigation. In these type of dual plumbed communities, potable water can be used as a backup for the non-potable supply. Increasing the use of reclaimed water while using the potable water supply as a backup for unexpected non-potable water interruptions increased the risk for cross-contamination.

With the safety of the community water supply being the main priority, the design engineers reached out to Metropolitan Industries for their expertise.

We, along with the project specifiers, followed the regulatory guidelines to provide a positive means of backflow prevention by using an air-gap tank as a method for maintaining compliant cross connection control.

Additionally, this project required pumps to help repressurize the facilities’ water supply downstream of the air-gap tank. We went with the trusted multi-stage centrifugal pumps as their operations are stable over a wide range of flows. The typical selections for this pump will have a 10-1 turn-down ratio.

Our air-gap tank solutions are customized to meet the unique needs of project partners. However, standard factors, i.e., backflow prevention, turbulence, and entrained air control, always need to be considered when sizing any air-gap tank project.

Our systems are always complemented by the latest technological control capabilities. Control systems include programmable logic controllers for precise pressure control on variable flow systems. Touchscreen operator interface terminals provide an intuitive means of monitoring status and adjusting system setpoints. Control systems can be seamlessly integrated to plant controls or building automation systems via ethernet or BACnet.

Air-gap break tank systems, available for both indoor and outdoor locations, are manufactured as fully integrated and prefabricated packages to include tanks, pumps, piping, valves and controls. All manufacturing is done in our on-site facility, which guarantees a single source for service, support, and warranty.

As industry leaders, we remain diligent in helping municipalities across the nation succeed in their water conservation goals. By staying on top of water conservation trends, understanding federal guidelines, and developing innovative technology, our team offers the high-level support needed for a successful water reclamation project. Our solutions and guidance will not only meet the regulatory guidelines but will also help protect your community at large.

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