Demand of rural area survey 2019, 1.77% growth

Survey year 2019; base period 2 years and design period 20 years, so the design year is 2041, i.e. $n = 22$ years after the survey.

Design population

$$P_{2041} = 4460\times(1.0177)^{22} = 6{,}561$$

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. Losses and wastage are 15% of net demand as given. Student and livestock numbers are taken as constant.

Losses and wastage $= 15\%$ of net demand $= 49{,}840$ l/day

$$Q_{avg} = 332{,}265 + 49{,}840 = 382{,}105\ \text{l/day} = 382.10\ \mathrm{m^3/day} = 4.42\ \text{l/s}$$

Answer: Design population = 6,561; total water demand = 382 m$^3$/day (4.42 l/s).