当提供给工业用户进行间接再利用的公有处理厂（POTW）的再生水返回同一POTW进行处理时，再利用水可能成为一种负担。随着循环再利用水量的增加和保守污染物的集中，POTW的处理工艺、污泥质量或废水排放标准最终将出现问题。同样的污染物浓度累积也可能导致工业用户（积垢离子）或其他再用水用户无法接受再用水。 确定问题污染物、问题何时何地发生以及替代解决方案需要了解整个水循环。具体的解决方案可以很多，但是选择最佳的解决方案必须考虑总的水系统；POTW、水厂和水源。使用大量水的行业，如发电机和计算机芯片制造商，更频繁地使用再生水资源。这些行业通常会以相同或增加的保守污染物质量将回用水排放回POTW。 保守污染物是指在POTW工艺中通常无法去除的污染物，如金属和盐，会在回收水中积聚。总溶解固体（TDS）或盐类正成为执行废水再利用的水务部门的主要关注点。在直流系统中，TDS的增加通常不是问题。然而，当再生水被重新利用并返回到其来源的废水处理厂时，TDS将开始在系统中累积。包括数字。

Reuse water can become a liability when reclaimed water from a Publicly Owned Treatment Works (POTW) that is provided to industrial customers for indirect reuse is returned to the same POTW for treatment. As the volume of recycled reuse water increases and conservative pollutants are concentrated, eventual problems will occur with the POTW's treatment process, sludge quality or effluent discharge standards. The same pollutant concentration build-up can also cause the reuse water to become unacceptable to the industrial user (accumulation of scale forming ions) or other users of reuse water. Identifying the problem pollutants, when and where problems will occur, and the alternative solutions will require an understanding of the total water cycle. The specific solutions can be numerous, but selection of the best solution must consider the total water system; the POTW, water plant, and source water. Industries that use significant amounts of water, such as electric power generators and computer chip manufacturers, are more frequently using reclaimed water sources. These same industries will typically discharge the reuse water back to the POTW with the same or increased mass of conservative pollutants. Conservative pollutants are pollutants that are not typically removed in a POTW process, such as metals and salts, and will accumulate in the recycled waters. Total Dissolved Solids (TDS) or salts are becoming a major concern to water authorities that practice wastewater reuse. In once through systems, TDS increases are usually not a problem. However, when the reclaimed water is reused and returned back to the wastewater treatment plant from which it came, then TDS will begin to accumulate in the system. Includes figures.