加利福尼亚旧金山市和县正在开发一个水循环总体规划。该计划的目标之一是利用循环水灌溉、冲厕和冷却水，以便提供更多优质水用于扩大饮用水供应。旧金山再生水最大的潜在用途是景观灌溉，主要客户是城市的娱乐和公园部门。本文介绍了1993年实施的一项试点研究的现状，该研究旨在确定用再生水灌溉城市公园植物的不良影响（如果有）。用循环水和控制水（饮用水或非饮用水）灌溉同一套植物。 试验研究设计要求灌溉草坪和木质区域，以及苗圃园丁选择的26种容器植物。循环水中令人担忧的成分是硼、钠和氯化物，它们会导致植物生长减少、颜色变差，并会影响土壤渗透性。对植物组织和土壤样本进行分析，以测量再生水对植物的任何影响。每月对植物进行物理观察和拍照，以跟踪植物叶片、开花或生长的变化。到目前为止，这项研究发现使用循环水灌溉几乎没有负面影响。

The City and County of San Francisco, California, is developing a water recycling master plan. One of the plan's goals is to utilize recycled water for irrigation, toilet flushing and cooling water so that more high quality water will be available for expanding potable supplies. The greatest potential use for reclaimed water in San Francisco is for landscape irrigation, and the primary customer is the city's Recreation and Park Department. This paper presents the current status of a pilot study that was implemented in 1993 to determine the adverse effects, if any, of irrigating city park plants with reclaimed water. Identical sets of plants were irrigated with recycled water and with control water, either potable or non-potable groundwater. The pilot study design required irrigating a turf and woody area, and 26 species of container plants selected by nursery gardeners. Constituents of concern in the recycled water are boron, sodium and chlorides, which can cause plants to experience reduced growth, poor color, and can affect soil permeability. Analyses are conducted on samples of both plant tissue and soil to measure any effect the reclaimed water has on plants. Physical plant observations and photographs are made monthly to track changes in plant foliage, flowering or growth. The study to date found very few negative effects of irrigating with recycled water.