52/Plumbing Engineer March 2019

science for DPR as well as indirect potable reuse is well- established and de facto legal in several states. The whole notion that water is a waste product after a single use is not only unsustainable but fundamentally wrong. To maximize water reuse, one must determine where the water for reuse originates and what one plans to do with it once treated. There are three categories of used water - greywater, which is relatively clean water from showers, bathtubs, sinks and washing machines; blackwater, con- taining feces, urine and flush-water from toilets and anal cleansing water; and what has become known as dark grey- water, which is kitchen effluent. However, dark greywater is not yet reliably defined in the Uniform Plumbing Code and requires absolute definition if we are to implement water reuse standards effectively. Depending on the treatment and desired outcome of the treated water, we end up with either potable or nonpotable water, which is clearly defined by the U.S. Environmental Protection Agency and the World Health Organization. Water usage plays an important part in determining where and how water should be reused. In arid or semi-arid regions, such as Southern California, roughly half the water usage is for irrigation of lawns, landscaping and yards. A big push by local authorities has resulted in the installation of drought-tolerant landscaping and smart watering control- lers that significantly reduce outdoor water usage. expansion to incorporate the demand of the smart city concept. Current standards and regulations often conflict with each other, causing confusion and, for the smart city future, are mostly inadequate. Specific standards for water reuse require a great deal of expansion from defining each of the wastewater sources and treated water classifications to composing meaningful standards in the interests of water conservation, reclamation and reuse. Treating and delivering water in any form requires power and constant monitoring, ideally achieved centrally to offset the cost and maintain control over potential public health implications. Multiple competency standards - such as electrical, mechanical, plumbing, energy and networking (communications) - as well as architectural guidance must be incorporated into guidelines and ultimately into new standards. They must be flexible and rapidly adaptable to facilitate the pace of innovation and to compensate for new scientific findings. While some states such as Arizona, Oregon, New Mexico and Texas have shown more progress in water reuse regula- tions, others are reluctant to expand their current thinking. There is certainly room for improvement and a willingness to publicly beta test with remote supervision, the Internet of Things (IoT) and adequate telemetry needs implementation. Arizona, for example, has aggressively pursued direct potable reuse (DPR), the holy grail of water reuse. The

Water Reuse