Rural village demand, survey 2070 BS, base year 2073

Survey year 2070 BS, base year 2073 BS and design period 20 years: the service (design) year is $2073+20 = 2093$ BS, which is 23 years after the survey.

Population and students in the design year

$$\begin{aligned} P_{2093} &= 5000\times(1.015)^{23} = 7{,}042\\ S_{2093} &= 350\times(1.01)^{23} = 440 \end{aligned}$$

Water demand

Design values assumed (Nepal rural water supply practice): domestic 45 lpcd (public taps); day scholar 5 l/d; boarder 45 l/d; office staff 45 l/d with 10 staff per office; big animal (cow, buffalo) 45 l/d; small animal (goat, pig) 5 l/d; poultry 0.2 l/d; health post 1000 l/d; tea shop 500 l/d; losses and wastage 15% of net demand; maximum day factor 1.5 and peak hour factor 3. Livestock numbers are taken as constant.

Losses and wastage $= 15\%$ of net demand $= 48{,}808$ l/day

$$Q_{avg} = 325{,}385 + 48{,}808 = 374{,}193\ \text{l/day} = 374.19\ \mathrm{m^3/day} = 4.33\ \text{l/s}$$

Answer: Total water demand of the village in 2093 BS = 374 m$^3$/day (4.33 l/s), for a design population of 7,042.