As society further recognizes the cost of large-scale district or municipal water treatment plants to treat water to potable water standards, as well as the cost of building and maintaining large potable and wastewater infrastructure systems, moving more to localized systems makes more sense. But using a community-wide treated water supply as a sole source of water for landscape purposes is an expensive waste, especially in terms of the energy used to treat and pump it. This cost can rise exponentially if expensive lift stations are required in your area due to topography. Rainwater makes much more sense, and it is better for your plants as well. Additionally, the fluoride and chlorine added to municipal water kills all of the beneficial microorganisms that convert soil nutrients into a form that plants can use.
In a net zero water world, each home would be limited to the amount of water that can be captured, used and reused on its site. This strategy is the only source of income for many people worldwide. Think about those populations that live on islands, places like Bermuda and the US Virgin Islands, where homes are designed for rooftop collection and underground cistern storage. Relying only on their ability to capture and store rainwater and water reuse has provided all their water needs since such places were inhabited.
For the purposes of this this article, we will also use the model where all our water is captured through rainwater collection. If our goal is a sustainable water source, what other means is as reliable as this? Both indoor potable water and non-potable water can be obtained from rainwater.
Rainwater is a renewable resource and an excellent source of high-quality water. “Captured onsite” does not mean the ability to drill a well into shared water supplies and have unlimited access to those supplies. Ground and surface water resources must be set aside as dedicated to ecosystems, wildlife, agricultural needs and emergency and fire defense. We are going to limit those enough when we all start capturing and using as much of the water that falls on our sites as we can.
To achieve water independence, we must incorporate numerous methods of capture and provide separate storage facilities for various uses, each defined by quantity and the type of sanitation treatment required. Some water could be captured and stored within the land itself. Other capture will require some type of container or cistern for storage, but no type of treatment for its use. And, finally, water for potable purposes would require separate storage in a food-grade cistern, with an onsite treatment system. Beyond the various initial means of capture and use, reuse of water will require additional systems for storage and treatment. All of these activities require significant thought with regard to separation of plumbing pipes to protect water quality and safety.
If we look closely, we can see that this is a viable basis for developing sustainable water conservation practices. For some dense developments, this may mean that a community-wide system is in place to capture water on all rooftops for centralized storage and distribution. We currently are seeing this type of design applied to renewable energy production, utilizing the rooftops of commercial buildings to house large solar arrays to provide electric power to surrounding neighborhoods. At some point, those same rooftops may collect rainwater to be stored in large reservoirs beneath the foundations of those buildings for the same purpose of supplying neighborhood needs. Only when these types of developments share community agricultural garden space would other water resources, including regional groundwater and surface water supplies, be made available.
