Table 3.

Comparison of monitoring results with quality requirements for toilet flushing from 18 selected wastewater reuse specifications (details in Table S5). The type of requirement (max/min concentration, max/min average, or min removal) is specified in brackets. The column “quality requirements met” describes the percentage of requirements that were met (compared to the number of specifications that give requirements for the parameter) and is categorized into all (100%), mostly ($\ge$90%), partially ($\ge$50%), mostly not (<50%) or none (0%) of the specifications were met.

Parameter	Range of requirements	Quality requirements met
		P1 Hand Washing Station Zurich	P2 Hand Washing Station Durban	P3 Toilet System Durban
Chemical composition
COD (mgO2/L)	50-100 (max), 50 (max avg)	n/a	all	all
TOCa (mgC/L)	5 (max), 3 (max avg)	all	n/a	n/a
Total nitrogen (mgN/L)	1.6–7.8 (max), 70% (min removal)	all	all	partially
Ammonium (mgN/L)	6 (max), 4 (max avg)	all	all	mostly not
Total phosphorus (mgP/L)b	0.2 (max), 80% (min removal)	partially	partially	partially
pH (−)	6–9.5	all	all	all
Hygiene
Residual chlorine (mg/L)	0.2–5 (min), 0.5 (min avg)	none	mostly not	none
E. coli (#/100 mL)	<1–200 (max), <1–20 (max avg)	all	all	all
Total coliforms (#/100 mL)	0.3–240 (max), 2.2–23 (max avg)	n/a	all	allc
Appearance
Color (Pt/Co)	15-30 (max)	n/a	all	all
Turbidity (NTU)	0.5–10 (max), 0.2–5 (max avg)	n/a	mostly	mostly
TSS (mg/L)	5-1500 (max)	n/a	all	all

^aTOC $\approx$ DOC.

^bMeasured phosphate.

^cExcluding one sample that was presumably contaminated during sampling or analysis.