Elucidating drinking water quality deterioration in premise plumbing

住宅管道是与私人或公共建筑（如家庭、学校）相关的配水系统的一部分。与主分配系统相比，住宅管道具有独特的特性，使其更容易受到水质恶化的影响，例如更长的停滞期，更高的表面积与体积比以及温度升高。楼宇水管水质亦不受大多数规管制度监察。由于优先节约用水和提高管道装置效率，水龄的增加增加了由于氯衰变和由此产生的表面附着微生物群落（生物膜）的繁荣而导致水质退化的风险。有明确的证据表明，与传统建筑相比，节水建筑可以支持10-10000倍的机会性病原体。此外，在美国，估计有8%的水源性暴发（不包括军团菌）与住宅管道缺陷有关，并且住宅管道暴发的比例正在增加。除了微生物风险之外，住宅管道也被认为是无机污染物在化学或生物膜介导的沉积物中积累的场所。积累的无机物，如砷（as）（致癌物）、铅（Pb）和锰（Mn）（神经毒素），一旦积聚在表面上，这些毒素就会释放到水中，对公共卫生构成威胁。虽然前提管道被认为在治理无机水质恶化方面具有重要作用，但它尚未成为控制实验室研究的重点。目前尚不清楚管道材料、延长的停滞时间和节水配置如何影响无机污染物的积累和释放。这个独特的研究项目将识别、表征和探索控制室内管道中无机污染物（如砷、铅、锰）积累和释放的潜在生物和化学机制。HQP将在跨学科环境中进行培训，并通过三个相互关联的目标探索这些机制，这些目标将审查：(1)管道材料的影响；Ii)滞水/水龄的作用，包括模拟节水建筑的低流量情况；(3)上游水质和平衡转移的影响。该研究项目将对无机物积累和释放的具体生物和化学机制（例如，金属结合的关键官能团；金属表面沉积的结构和特征）提供基本的机制见解。这项研究产生的新知识将解释在加拿大和全球的室内管道、新装备的监管机构和公用事业中管理无机污染物积累/释放的潜在机制和环境条件，以做出合理的循证决策，最大限度地减少暴露风险并保护公众健康。

Premise plumbing is the portion of the water distribution system associated with private or public buildings (e.g. homes, schools). Compared to the main distribution system, premise plumbing has unique features that make it more vulnerable to water quality deterioration, such as longer stagnation periods, higher surface area to volume ratios, and elevated temperatures. Premise plumbing water quality is also unmonitored by most regulatory regimes. Increased water age, a result of water conservation priorities and improved plumbing fixture efficiency, heightens the risk of water quality degradation due to chlorine decays and the resultant flourishing of surface attached microbial communities (biofilm). There is clear evidence that water-efficient buildings can support 10-10000 times more opportunistic pathogens relative to conventional buildings. Further, an estimated 8% of waterborne outbreaks (excluding Legionella) in the USA are associated with premise plumbing deficiencies, and the proportion of premise plumbing based outbreaks is increasing. Beyond the microbiological risk, premise plumbing has also been implied as a site for inorganic contaminant accumulation in both chemically or biofilm mediated deposits. Accumulated inorganics, such as arsenic (As) (carcinogen), lead (Pb) and manganese (Mn) (neurotoxins), represent a public health threat given that once accumulated on a surface, these toxins can be released into the water. Although premise plumbing is implied to have a significant role in governing inorganic water quality deterioration, it has not been the focus of controlled laboratory study. It is unclear how pipe materials, extended stagnation times, and water efficient configurations influence the accumulation and release of inorganic contaminants. This unique research program will identify, characterize, and explore the underlying biological and chemical mechanisms that govern the accumulation and release of inorganic contaminants (e.g. As, Pb, Mn) in premise plumbing. Ten HQP will train in an interdisciplinary environment and explore these mechanisms through three interrelated objectives that will examine i) the influence of pipe materials; ii) the role of stagnation/water age, including mimicking low flow conditions of water-efficient buildings; and, iii) the impact of upstream water quality and equilibrium shifts. This research program will grant fundamental mechanistic insights into the specific biological and chemical mechanisms (e.g. key functional groups for metal binding; metals surface deposit structure and characteristics) through which inorganics can accumulate and release. The new knowledge generated by this research will explain the underlying mechanisms and environmental conditions that govern inorganic contaminant accumulation/release in premise plumbing, newly equipping Regulators and Utilities in Canada, and globally, to make sound evidence-based decisions to minimize exposure risk and protect public health.