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Water Storage: in A Building, Provision Is Required To Be Made For Storage of Water For The Following Reasons

This document discusses water storage requirements for buildings. Water is stored to meet intermittent or peak water demands, reduce pressure on main water lines, and provide water for firefighting. Water can be stored in overhead tanks or underground tanks. The required storage capacity depends on factors like hours of water supply, usage, and consequences of running out of water. Guidelines are provided for calculating storage capacities based on daily water demand and whether only overhead tanks, only underground tanks, or both are used. Minimum requirements and considerations for tank construction materials and features are also outlined.

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Pramod Patil
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295 views4 pages

Water Storage: in A Building, Provision Is Required To Be Made For Storage of Water For The Following Reasons

This document discusses water storage requirements for buildings. Water is stored to meet intermittent or peak water demands, reduce pressure on main water lines, and provide water for firefighting. Water can be stored in overhead tanks or underground tanks. The required storage capacity depends on factors like hours of water supply, usage, and consequences of running out of water. Guidelines are provided for calculating storage capacities based on daily water demand and whether only overhead tanks, only underground tanks, or both are used. Minimum requirements and considerations for tank construction materials and features are also outlined.

Uploaded by

Pramod Patil
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Water Requirement-Quantity

Water Storage
In a building, provision is required to be made for storage of water for the following reasons:
 Supply water in case of intermittent supply
 Meet the peak flow requirement with in building if same is not met by the city mains.
 To reduce the maximum rate of demand on the mains
 To maintain a storage for the fire fighting requirement of the building
 Provide for interruption in water supply if the mains are shut off for repairs or if there is
power failure.

The water may be stored in:


 overhead tanks (OHT) and/or
 Underground tanks (UGT).

The storage capacity or quantity of water to be stored for building will depend on:
 Hours of supply
 Rate and regularity of supply
 Usage
 Pressure in the mains
 Frequency of replenishment of overhead tanks, during the 24 h
 Consequences of exhausting storage particularly in case of public buildings like
hospitals.
 Fire storage & other requirement
Water storage capacity calculation:
In case of intermittent water supply, the following guidelines should be adopted for calculation
of capacity:
 When the supply is from main OHT
o the capacity of individual OHT may be taken as: half a day demand (50% or @0.5)
 In case of all the other buildings (apartments, hotels, hospitals, and commercial)
o the capacity of UGT may be taken as: one and a half day’s demand (150% or @1.5)
and
o and OHT may be taken as: half a day demand (50% or 0.5)
 Wherever raw water and treated water are stored in separate UGT’s
o the combined storage capacity shall be of: one and a half day’s demand (150%
or @1.5
 In case of sewage treatment plant, for treated water storage in respect of flushing,
o one day flushing demand shall be stored in flushing UGT or treated effluent
storage tank which is part of the plant (100% of flushing or @ 1)
o half a day demand shall be stored in OHT (50% or @0.5)
o One day irrigation water demand shall be added to UGT if for landscaping &
gardening.

Minimum requirements for calculation of capacity of these storage tanks are as follows:
 In case only OHT is provided, it may be taken as
o 33.33% to 50% of one day’s requirement (0.33)
 In case only UGT is provided, it may be taken as
o 50% to 150% of one day’s requirement (0.5-1.5)
 In case combined storage is provided, it may be taken as
o 66.6% UGT one day’s requirement (0.666)
o 33.33% OHT of one day’s requirement (0.3333)
Note:
 When HNP system, there might be no OHT in this case, UGT size should be 200% or
@2.0
 From above block we can note that the total storage must be twice of the daily
requirement.

Material of construction for Tanks:

 Masonry/Concrete
 Galvanized iron Sheets
 Mild steel sheets
 Fiber FRP
 High density Polyethylene (HDPE)

Each tank shall be provided with the following:


 Manholes
 Ladders
 Overflow pipe/Warning pipe
 Vent pipes —
 Drain pipe
 Scour pipe —
Preventions & considerations:
 The outlet pipe shall be fixed 50 mm to 75 mm above the bottom of the tank and fitted
with a strainer, preferably of brass.

 If the storage capacity required is more than 5000 liters, it is advantageous to arrange
it in a series of tanks so interconnected that each tank can be isolated for cleaning and
inspection without interfering with the supply of water.

 In large storage tanks, the outlet shall be at the end opposite the inlet to avoid
stagnation of the water.

 The underground tanks should not be located in low lying areas or near any public or
private sewer, septic tank, leaching pool or soakage pit to prevent any contamination.

 The overflow of the tank should be well above (preferably 600 mm) the external surface
level and terminate as a warning pipe with a mosquito proof grating.

 Vent pipe shall be provided with a mosquito proof grating.

 The elevation difference between the outlet pipe of the OHT and the highest fixture at
the top floor of the building is minimum 2 m.

 Water tank over flow & drain pipe sizes:

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