Access to adequate supplies of potable water is a key driver of human health. Physical and chemical treatment processes are frequently necessary to make water safe to drink. Monitoring of water before, during, and after treatment is an essential component of the provision of potable water, and most aspects of water quality monitoring require electronic devices to augment human senses. Every nation sets rules governing the treatment and monitoring of drinking water, in an attempt to continuously ensure potability of drinking water supplies. Presently, however, the regulations governing the design of common electronic devices for water quality monitoring are developed and published by just two organizations – the US Environmental Protection Agency (EPA) and the International Organization for Standardization (ISO). The implications of this regulatory situation on drinking water quality monitoring, particularly in low-resource settings, are largely (perhaps completely) unaddressed in existing literature.
Turbidity, which may be summarized as cloudiness in a body of liquid due to the scattering of light by particles suspended in that body, is internationally recognized as a simple and useful monitoring parameter for drinking water treatment. Using turbidity as an exemplar, this dissertation examines the structure of regulations governing the design of water quality monitoring devices, and the potential impact that regulatory structure has on the design, fabrication, and marketing of water quality monitoring devices, including both closed-source and open-source technology. National turbidity monitoring requirements for several nations, and the turbidity guidelines promulgated by the World Health Organization, are compared. The EPA and ISO turbidimeter regulations are also examined in relation to these national and international turbidity monitoring requirements. Design variables and requirements are identified which are generally necessary to ensure a properly functioning turbidimeter, but which are not explicitly stated in EPA and ISO turbidimeter regulations.
Aspects of the commercial turbidimeter market, and EPA and ISO turbidimeter regulations, which are likely burdensome for water quality monitoring efforts in low-resource settings (such as rural communities in developing countries), are explored – perhaps chief among these being cost. While production of open-source turbidimeter designs provides a potential solution for turbidity monitoring in low-resource settings, open-source turbidimeter design efforts are currently far from able to meet global needs.
To provide supplementary regulatory requirements for EPA and ISO turbidimeter standards, and to spur the development of market-ready open-source turbidimeter designs, a framework titled the Affordable Water Quality Analysis (AWQUA) device development is proposed. It consists of a turbidity-specific regulatory section, and a general water quality monitoring device development guidance section. Proper use of this guidance section is intended to strengthen open-source water quality monitoring device development efforts and encourage the production of device documentation suitable to demonstrate compliance with the regulatory section.
An important contribution of this dissertation effort is the development and detailed description of four different examples of novel, low-cost, open-source water quality monitoring devices that motivated the proposed supplementary framework, informed its design, and serve to illustrate its application. First, a low-cost, open-source handheld turbidimeter based on a simple digital light detection sensor is detailed and discussed. The design, fabrication, and testing of this device served as a motivator for the development of the proposed supplementary turbidimeter development guidelines proposed. The turbidimeter nearly meets international regulatory guidelines, was fully described in a peer-reviewed publication, and is believed to be the most detailed open-source design of a digital turbidimeter publicly available (at the time of this writing) and yet contains several subtle but critical design flaws that are unaddressed in current national and international turbidimeter regulations. This prototype thus motivated and informed the design of the proposed new regulatory framework. Subsequently, three other promising open-source water quality monitoring designs were developed, fabricated, and evaluated under the AWQUA Framework: (1) a second low-cost open-source handheld turbidimeter, based on a highly precise light-to-voltage analog sensing setup; (2) a highly compact low-cost open-source inline turbidimeter, designed for continuous immersive monitoring of turbidity in surface waters; and (3) a low-cost open-source jar tester – a device used to evaluate certain physical and chemical treatments employed in drinking water treatment to reduce turbidity. These designs and the associated framework that grew from them are contributions toward the provision of “Affordable Water Quality Analysis” (AWQUA) capabilities for communities in low-resource settings
