What’s an “Onsite Non-potable Water System”?
- Onsite: Placed in a location that varies from single-family-residential up to a district or neighborhood (i.e. not a centralized municipal system that crosses many neighborhoods)
- Non-potable: Not drinkable (but still good for many other uses!)
- Water: That substance that we’re all mostly made of that we can’t live without for more than a few days.
- System: A collection of treatment, storage, and conveyance hardware and/or software.
Put all these words together and onsite non-potable water systems include:
- Rainwater harvesting
- Condensate harvesting (water from the air)
- Stormwater harvesting
- Reuse of water from fixtures without sewage (e.g. sink, tub/shower)
- Reuse of water from fixtures with sewage (e.g. toilet)
When properly planned, designed, constructed, and maintained, these systems have numerous benefits over conventional “waste” and water treatment systems. Generally, onsite water reuse systems often do two or more of the following:
- Save and/or generate money
- Protect public health
- Preserve instream flows and fish habitat
- Promote resilience
- Enhance emergency preparedness
- Save and/or generate energy
Choose from the following talking points based on your audience:
(Click here to jump to Social Benefits, Financial Benefits, Water Quality Benefits, Water Quantity Benefits, Other Environmental Benefits, Resilience Benefits)
Public Health Benefits
- Free model codes and ordinances are available for under-resourced jurisdictions. Language for onsite non-potable water systems has been developed by health and environmental agencies in 11 states and the District of Columbia for use in other local and/or state programs. It’s now possible to develop permit programs using an internationally-accepted approach that is more protective of public health than current Environmental Protection Agency standards for conventional water systems. Source: National Blue Ribbon Commission for Onsite Nonpotable Water Systems, Source: Water Environment & Reuse Foundation (WE&RF)
- Proper sanitation prevents disease. As populations grow, demands on our drinking water systems can be alleviated by reusing onsite water for non-potable uses. Non-potable water reuse can reduce domestic water use by up to 60% when applied to non-potable end uses such as irrigation and toilet flushing. Source: US Department of Energy
- Equitably provide a means of self-reliance. Smaller systems with a lower upfront cost are easier to finance, allowing for communal ownership. Onsite water systems generate a water supply that can be sold to pay off the systems and generate a profit for those communities.
- Generate good-paying green jobs. Onsite non-potable water systems would be numerous, distributed, and smaller than a single conventional water or wastewater treatment plant, creating opportunities for planning, design, constructing, and especially maintaining and operating these systems. Source: Making the Utility Case for Onsite Non-potable Water Systems
- Enrich building occupants’ relationship with water. People living in buildings that generate their own water supply tend to be more aware of the water they’re using and what they’re putting in the drains. Onsite non-potable water systems can create a greater appreciation for water and good habits around conservation and preventing pollution. Source: Puttman Infrastructure tour of Hassalo on 8th
- Enhance livability. Vegetated onsite water treatment systems are the easiest to maintain with lowest energy demand. “Green infrastructure” like this reduces crime, lowers traffic speeds, gives site users a sense of well-being and more. Source: Green Cities: Good Health
- Create an opportunity for art. Onsite water systems often have tanks and other structures that can be artfully integrated into the landscape and architecture.
- Avoid large capital improvement costs. Decentralized systems can be integrated into centralized system infrastructure, avoiding large capital improvement costs by reducing the need to expand municipal water and wastewater systems. Source: Environmental Protection Agency
- Blending water supplies optimizes affordability. Across the United States, onsite water systems are being privately developed and operated, proving that these systems are cost-effective and will even generate a profit. Switching from single or dual water supply to a diversified water portfolio will allow public agencies to integrate these systems into existing infrastructure to optimize cost-savings for ratepayers.
- The cost to upgrade our existing centralized municipal water infrastructure increases every year. “The total investment gap through 2025 is expected to be $105 billion, and $152 billion, by 2040 if left unaddressed. This doesn’t include replacing more than 7.3 million lead service pipes, which adds at least $30 billion to the investment gap.” Large municipal system move massive amounts of water and nutrients across large areas and may not be the most sustainable investment. Source: American Society of Engineers
- Reduce algae blooms and other low flow impacts. Using water more than once leaves more water in the environment to lessen the frequency and impact of low flows. (Source: Environmental Protection Agency) Trout Unlimited’s Coastal Streamflow Stewardship Project demonstrates how rainwater harvesting can solve timing problems to reduce draws during low flow periods.
- Protect sensitive waterways. Water reuse has been used to reduce or eliminate wastewater discharges where excess nutrients would impact sensitive waterways. On the other hand, water with high levels of nutrients would be beneficial for irrigation, keeping water onsite.
- Reduce and prevent pollution. Stormwater and wastewater reuse lowers the amount of pollution entering a waterway. Where combined sewers are carrying both these waters, combined sewer overflow events occur less often. Source: Environmental Protection Agency
- Minimize flooding. One type of onsite water system captures rainwater and stores it in a tank for reuse and can reduce flooding. “Active” rainwater harvesting systems, which integrate this water supply with a conventional stormwater runoff detention system , have been found to be even more effective for reducing runoff and promoting a cleaner surface water supply. Source: Environmental Protection Agency
- Enhance wetlands and groundwater supply. Reusing water more than once relieves pressure on groundwater supply needs, which are hydrologically connected to wetlands and influence the health of their ecology. Source: Environmental Protection Agency
- Protect watershed health with small-scale approaches. Conventional municipal systems usually draw a lot of water from one watershed and pump and convey it long distances. After people use it, those large volumes of wastewater are conveyed long distances, treated, and discharged to a entirely different watershed. While the downstream may experience beneficial stream restoration, plants and animals in both watersheds can be impacted by downstream flooding and upstream drying out. Onsite water systems can capture, treat, use, reuse, and discharge water all within a small, localized area, much smaller than a watershed. Source: Eco-environmental impact of inter-basin water transfer projects: a review
- Reduce urban heat island effect. The urban heat island effect impacts communities by increasing summertime peak energy demand, air conditioning costs, air pollution and greenhouse gas emissions, heat-related illness and [deaths], and water quality.” Increasing tree and vegetation lowers surface and air temperatures by shading and cooling. To conserve drinking water, non-potable onsite water should be used to irrigate these landscapes. Source. Purdue University, EPA: Heat Island Effect
- Reduce energy. At over 8 pounds per gallon, water is heavy. Any time water must be pumped (which occurs in almost every system at some point) energy demands increase. Onsite water systems usually convey and pump water over much shorter distances than conventional municipal systems. Source: Environmental Protection Agency
- Minimize fire damage to buildings. Increasing vegetation, like planting more trees, is an effective approach to restore local and global climate regulation. Wetter and cooler soils slow the spread of and intensity of fires, and irrigating with non-potable water can aid establishing vegetation, especially in drought-stricken areas. Source: United States Department of Agriculture, Forest Service
- Reduce resources used in the treatment process. Conventional water systems treat all water to the same level of quality, whether we’re drinking it or flushing toilets with it. Instead of treating all water to a single drinkable standard, onsite waters can be treated to a level that considers their end use and disposal point (e.g. water draining to a municipal wastewater treatment plant versus irrigation), which is also known as “fit for purpose” water.
- Diversify a community’s water portfolio. Many places purchase or receive water from outside of their own jurisdiction. Non-potable onsite water reuse systems provide a local, alternate water supply. Source: Environmental Protection Agency
- Improve emergency preparedness. Onsite non-potable water systems often include smaller, distributed storage ponds and tanks to support a more resilient and robust infrastructure. Additionally, when water is harvested from a roof, reliance on buried pipes are avoided, making continuous water access more likely in widespread fire and earthquake events.