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Although customer demand is minimal at night, there is still a small amount of flow in the system owing to night-time customer demand for such uses as toilet flushing, washing machines, etc. This flow is termed ‘EMNF’ (Werner 2011). In urban situations, about 6% of the population will be active during the minimum night-time flow period (McKenzie 1999). Apart from the MNF data, the SANFLOW model also requires basic infrastructure variables as presented in Tables 2 and 3. Where there was no data such as leakage coefficients and pressure correction factors, some assumptions were made and SANFLOW default values that were recommended by McKenzie (1999) were used. Household size was adopted from the 2012 Census Report to be 4.2 people (ZIMSTAT 2012) in order to estimate the population served by the total number of connections.

Table 2

Infrastructure variables used in SANFLOW model

 Value
DescriptionBudiriroGlen ViewBelvedereMabelreign
Length of mains (km) 90.2 109.9 98.5 94 
Number of connections 11,400 11,100 1,900 3,200 
Number of properties 11,400 11,100 1,900 3,200 
Estimated population 47,880 46,620 7,980 13,440 
 Value
DescriptionBudiriroGlen ViewBelvedereMabelreign
Length of mains (km) 90.2 109.9 98.5 94 
Number of connections 11,400 11,100 1,900 3,200 
Number of properties 11,400 11,100 1,900 3,200 
Estimated population 47,880 46,620 7,980 13,440 
Table 3

Leakage parameters used in SANFLOW model as recommended by McKenzie (1999) 

 Value
DescriptionDefaultBudiriroGlen ViewBelvedereMabelreign
Background losses from mains (L/km.hr) 40 40 40 40 40 
Background losses from connections (L/conn.hr) 
Background losses from properties (L/conn.hr) 
% of population active during night 
Quantity of water used in a cistern (L) 10 10 10 10 10 
Background losses pressure exponent 1.5 1.5 1.5 1.5 1.5 
Burst/leaks pressure exponent 0.5 0.5 0.5 0.5 0.5 
Exceptional use m3/hr – – – – – 
 Value
DescriptionDefaultBudiriroGlen ViewBelvedereMabelreign
Background losses from mains (L/km.hr) 40 40 40 40 40 
Background losses from connections (L/conn.hr) 
Background losses from properties (L/conn.hr) 
% of population active during night 
Quantity of water used in a cistern (L) 10 10 10 10 10 
Background losses pressure exponent 1.5 1.5 1.5 1.5 1.5 
Burst/leaks pressure exponent 0.5 0.5 0.5 0.5 0.5 
Exceptional use m3/hr – – – – – 

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