Peer-Reviewed

Nanotechnology offers the promise of new materials and technologies through manipulation of physical and chemical properties and system behaviors that are controlled by size— very small particles behave differently from larger ones. Nano-materials are those that have at least one dimension in the nanoscale (approximately 1 to 100 nm), and this feature alters their biogeochemical behavior. Nanomaterials are abundant and ubiquitous, naturally occurring in many global processes (e.g., from volcanic eruptions); incidentally formed in human activi-ties (e.g., from diesel exhaust emissions); and engineered for specific purposes (i.e., designed and tailored for novel applica-tions such as drug delivery, antifouling coatings, or improve-ments to mechanical strength). The potential health and safety risks of nanotechnology pose a concern for drinking water utilities because of their responsibility to protect public health by providing safe drinking water. The pres-ence of sub-micron particles (e.g., colloids, viruses, clays) in natural waters is well known (Buffle & Leppard 1995). Specific technolo-gies within drinking water systems are designed to remove these particles, some of which are naturally occurring at the nanoscale. Thus, existing regulations already indirectly cover some natural nanomaterials—e.g., turbidity and disinfection. Figure 1 shows size ranges for natural materials and engineered nanomaterials as well as removal ranges for treatment processes. The use of engineered nanomaterials (ENMs), which are designed and tailored for specific applications using novel shapes, configurations, and properties (e.g., size, shape, composition, reactivity), has led to questions about whether the unique characteristics that make ENMs appeal-ing for novel applications also make them more likely to persist in the environment or in drinking water treatment plants (DWTPs). There has been a strong effort toward proactive research of the human and environmental effects of nanotechnology, par-ticularly over the last five years (NRC 2012, NNCO 2011). For example, within the US National Nanotechnology Initiative’s proposed 2016 budget, over 10 % ($105 million) is dedicate