An Essential Guide to Potable Reuse
Clean, drinkable water is a basic necessity. The US Congress passed the Safe Drinking Water Act in 1974 to ensure every citizen could access this resource. Seasonal droughts and a changing climate have challenged municipal water systems as they maintain the drinking water supply. One of the strategies for addressing this problem is incorporating potable reuse into the water system.
While the EPA Guidelines for Water Reuse allow and encourage potable reuse, most water reuse practices focus on non-potable applications such as irrigation. However, more municipalities in water-stressed areas recognize the need to reuse water for the potable water supply.
What Is Potable Water?
What is potable water? Water that meets the standards for safe drinking is considered potable. For municipal water supplies, reaching potability involves treatments such as filtration, disinfection, and chemical balancing.
Common Uses of Potable Water
When water is potable, people can consume it with minimal health risks. The SDWA standards provide criteria for determining the safety of drinking water. While safe consumption is the primary goal, other uses of potable water include:
- Personal cooking
- Industrial food processing
- Bathing and other sanitary needs
- Pharmaceutical manufacturing
Current Challenges to Potable Water Systems
Some regions of the country have easy access to sizeable potable water sources. However, drought-prone areas such as the southwest are subject to chronic water shortages. As climate change continues to raise global temperatures, the number of regions with stressed drinking water supplies will expand.
Other areas deal with occasional water quality issues. Coastal regions may need to supplement the water supply when seawater compromises local groundwater resources. Areas that depend on natural reservoirs need supplemental solutions for seasonal changes like bacterial or algal growth.
Indirect and Direct Potable Reuse
The EPA Guidelines for Water Reuse outline two forms of water reuse: direct and indirect.
Indirect Water Reuse
Indirect reuse involves an intermediate step between water treatment and its release into the drinking water supply. A treatment plant might send effluent into a natural water source like a river, lake, or aquifer. Some water systems already incorporate de facto indirect reuse.
Direct Potable Reuse
Direct reuse involves moving effluent from a wastewater treatment plant directly into storage for use in the local water system. A direct system is often the most cost-effective strategy in areas with stressed water supplies.
Potable Water Treatment Strategies
Bringing wastewater to potable standards can be a challenge. Safe drinking water must exceed the purity levels of standard EPA wastewater guidelines. Wastewater plants must employ several treatment solutions based on local water conditions.
Sedimentation
Allowing gravity to pull solids out of wastewater is often the first step in water treatment.
Filtration
Several levels of filtration will remove suspended solids of various sizes.
Reverse Osmosis
Forcing water through a specially designed membrane can reduce chemical impurities.
UV Disinfection
Exposing water to ultraviolet light neutralizes biological impurities.
Chemical Stabilization
Adding substances like sodium hydroxide and calcium chloride can bring wastewater to a neutral pH.
Activated Carbon
Running water through activated charcoal traps molecules of harmful chemicals and substances that affect the taste of drinking water.
Public Perception of Reusing Potable Water
In general, the public is comfortable with recycling wastewater for non-potable uses. According to the EPA, about 80% of people surveyed approve of this use. Around half of the population recognizes that treated wastewater is potable, but only about 30% claimed to be comfortable drinking it. These results reflect what water experts call “the yuck factor,” knowing where recycled water has been before it comes out of the tap.
Other municipalities have expressed concern about social issues and water reuse. They want to know that reused water will be distributed equally throughout the system and not just to specific neighborhoods.
SCADA Technology and Potable Water Treatment
Supervisory control and data acquisition technology continue to grow as a beneficial resource for wastewater treatment plants and water distribution systems. Sensors throughout the system provide real-time information about water pressure, pH levels, and flow rates. At the central hub, managers can program the system to send alerts and respond automatically to unexpected changes. Adding SCADA to a water system will improve efficiency and prevent supply disruptions.
Incorporating a Cloud-Based SCADA Solution
High Tide Technologies designs and implements cloud-based SCADA technology for municipal water collection, treatment, and distribution systems. A system connected to the cloud allows employees to access data on any portable device for faster response times, intentional maintenance planning, and smoother operations. Contact us to learn more about the benefits of SCADA for your system.