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Table 3

Water reuse guidelines for toilet flushing in different countries

 ChinaaJapanbBritaincUSAdGermanye
pH 6.0–9.0 5.8–8.6 5–9.5 6.0–9.0  
Odor Not unpleasant Not unpleasant    
Turbidity (NTU) ≤5 ≤2 <10 ≤2  
Residual chlorine (mg/L) ≥1.0 after 30 min, ≥0.2 at point of use ≥ free: 0.1, or ≥ combined: 0.4 <2.0 ≥1.0  
Residual bromine (mg/L)   Not detectable   
Chromaticity ≤30     
DS (mg/L) ≤1,500     
BOD5 (mg/L) ≤10   ≤10  
     <5 
NH4-N (mg/L) ≤10     
LAS (mg/L) ≤1.0     
Fe (mg/L) ≤0.3     
Mn (mg/L) ≤0.1     
DO (mg/L) ≥1.0     
Total coliform (number/100 mL) ≤0.3  1,000  <104 
E. coli (number/100 mL)  Not detectable 250   
Intestinal enterococci (number/100 mL)   100   
Legionella pneumophila (number/100 mL)   Not detectable   
Fecal coliform (number/100 mL)    Not detectable <103 
Pseudomonas aeruginosa (number/100 mL)     <100 
 ChinaaJapanbBritaincUSAdGermanye
pH 6.0–9.0 5.8–8.6 5–9.5 6.0–9.0  
Odor Not unpleasant Not unpleasant    
Turbidity (NTU) ≤5 ≤2 <10 ≤2  
Residual chlorine (mg/L) ≥1.0 after 30 min, ≥0.2 at point of use ≥ free: 0.1, or ≥ combined: 0.4 <2.0 ≥1.0  
Residual bromine (mg/L)   Not detectable   
Chromaticity ≤30     
DS (mg/L) ≤1,500     
BOD5 (mg/L) ≤10   ≤10  
     <5 
NH4-N (mg/L) ≤10     
LAS (mg/L) ≤1.0     
Fe (mg/L) ≤0.3     
Mn (mg/L) ≤0.1     
DO (mg/L) ≥1.0     
Total coliform (number/100 mL) ≤0.3  1,000  <104 
E. coli (number/100 mL)  Not detectable 250   
Intestinal enterococci (number/100 mL)   100   
Legionella pneumophila (number/100 mL)   Not detectable   
Fecal coliform (number/100 mL)    Not detectable <103 
Pseudomonas aeruginosa (number/100 mL)     <100 

aUrban Wastewater Reuse Water Quality Standard for Urban Miscellaneous Water (GB/T 18920-2002) (AQSIQ 2002).

bNew criteria for the reuse of treated wastewater in Japan (Tajima et al. 2007).

cBritish Standard 8525-1:2010 (BSI 2010).

dWater Reuse Guidelines 2012 (EPA 2012).

eBerlin Senate (1995).

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