OHWT-UWT

1. Overhead Water Tank
A water tank is a container for storing water. Water tanks are used to provide storage
of water for use in many applications, drinking water, irrigation agriculture, fire suppression,
agricultural farming, both for plants and livestock, chemical manufacturing, food preparation as
well as many other uses.
Figure: Water tank in roof
Let,
6 storied apartment building
5 floor, 3 unit each
6 members per unit
Total = 6*3*5 = 90 persons
According to BNBC,
Water consumer rate = 40 gpcd (gallon per capita per day)
Total water consumption = 40*90 = 3600 gpd (gallon per day)
Assuming, pumping twice a day

2. Figure: Overhead water tank
Volume of water = 3600 * 10 = 36000 lb per day
= 36000 lb per day /62.4 lb per cft
= 580 cft per day
Pumping twice a day,
Volume of water = 580/2 cft
Plane area = 11*8 = 88 feet
Height of water = 290 cft / 88 feet square
= 3.38 feet = 3.5 feet
So, length= 11 feet, Width= 8 feet, Height= 3.5 feet
Figure: Reinforcement of water tank

3. Underground Water Tank
Figure: Underground water tank (casting)
Let,
6 storied apartment building
5 floor, 3 unit each
6 members per unit
Total = 6*3*5 = 90 persons
According to BNBC,
Water consumer rate = 40 gpcd (gallon per capita per day)
Total water consumption = 40*90 = 3600 gpd (gallon per day)
Assuming pumping twice a day
Volume of water = 3600 * 10 = 36000 lb per day
= 36000 lb per day /62.4 lb per cft
= 580 cft per day
Volume of Underground Water Tank = 580 * 2 cft per day
=1160 cft

4. Height of the underground water tank = (11’-1’-6”-5”) = 9.10 feet
Plane area of the surface = 1160 cft / 9.10 feet
=127.75 square feet
Assuming the length of the tank is 10 feet
So the width of the tank = 127.75 / 10 = 12.78 feet = 12.80 feet
So, Length= 10 feet, Width= 12.80 feet, Height= 9.10 feet
Figure: Underground water tank
Figure: Cross sectional view of a underground water tank