Maximum allowable values of the heavy metals in recycled water for household laundry

• Recycled water for washing machine has a great potential for urban water management.
• The paper presents maximum allowable values of heavy metals in recycled water.
• Cloth durability and washing machine durability are the decisive factors.

Household laundry as a new end use of recycled water in dual reticulation systems has a great potential as the significant amount of potable water from urban households can be saved. However, there is still no sufficient evidence and supporting recycled water quality guidelines for this particular use. A key gap in knowledge is the impact of heavy metals in recycled water on clothes and washing machines. Thus, this study aims to determine the maximum allowable values (MAVs) of the heavy metals iron (Fe), lead (Pb), zinc (Zn), copper (Cu), and manganese (Mn) in recycled water for washing clothes in washing machines. Six different concentrations of each targeted metals were prepared in tap water for the washing machine experiments. The tearing/tensile strength tests were used for the assessment of cloth durability. MINITAB 16 as a statistical tool was used and ANOVA one way test was applied for the significance analysis (Turkey's test p < 0.05). The results show that the MAVs of the heavy metals Fe, Pb, Zn, Cu and Mn were found to be 1 mg/l, 1 mg/l, 10 mg/l, 5 mg/l and 1 mg/l respectively in terms of cloth durability.