Understanding Formula for Water Pressure in a Tank
The formula for the pressure at a
depth, h in the water
A = area of base
h = height
g = gravitational field strength
p= density of liquid
Volume of liquid column, V = Ah
Mass of liquid column, m = pV = Ahp
Weight of liquid column, W = mg =Ahpg
The force acting on the surface area A is
the weight of the liquid column above it.
Pressure, = Weight of liquid column
Area of base of liquid column
P = hpg
Based on the normal water tank size for
The ranges of height are 0.53m to 1.65m,
therefore the water pressure is also ranged
between 5.3KPa to 16.5KPa
Why do we tap the vertical pipes?
• Vertical pipe: The water ﬂowing down the
conduit completely ﬁlls the conduit due to
natural gravitation force.
• Horizontal pipe: The water does not ﬁll the
conduit , the ﬂow is called channel ﬂow. Since
channel is not ﬁlled, no pressure diﬀerential
between ends of pipes unless there is a
mechanical forces placed in (pump).
Classification of Flow
Re = ρvD
-density is ρ ,
-diameter of pipe is D ,
-ﬂuid velocity is v
-viscosity is µ .
-Laminar Re <2000
The turbulent flow has a fluctuating v about some mean value. The flow rate is largest.
As a result
The pressure from the water tank P = hpg
With F=mg (where a=g)
P = F/A
P = mg/A
and A (area) is constant, while g is gravity flow with
viscosity is 1.002(Pa s, N s/m2) x 10-3
the viscous shear stress acting along the surface
cylinder viscous shear stress acting along the τ = τ(r)
surface cylinder is minimal in vertical pipe. Therefore
the force generated is based on natural water
pressure kept within the water tank.
Use the Bernoulli's equation of energy:
P/ρ + V²/2 + g*z = constant
P = pressure in Pa
ρ = water's density = 1000 kg/m³
V = velocity in section m/s
g = 9.81 m/s² (gravity acceleration)
z = height of the section from selected plane origin (we can
choose the ground)
Since the volume flow rate Q is constant and it is: Q = V*A with A
= section area (m²) and V = velocity m/s so... Q is in m³/s.
Now we have the area A1 = 1.2 cm² and Q1 = 60
cm³/s so V1 = Q1/A1 = 50 cm/s = 0.5 m/s.
The pressure is P1 = 5.3 kPa = 5300 Pa.
The energy is E1 = P1/ρ + V1²/2 + g*z1 with z1
the height from the ground (which varied
according to the location we want to have
Hence, the external parameters which WATUR
cannot control as derived from
E1 = P1/ρ + V1²/2 + g*z1
1. Depth of the water tank
2. Velocity of the water flow, which also
equivalent to the volume flow, Q
Yet, we can control the z1, the height of WATUR
from the ground
World first innovative idea crystallized after we
found the “hidden energy source” that runs
constantly in any building (homes, commercials,
industrials) water piping system.
An independent external energy harvesting system.
It tapes the natural gravitation of water flow and the
water pressure to harvest the energy and produce
Flexible: Could be installed at any parts within the water
piping system of any building to be used at washroom, kitchen
Cost Effective: Installation without major modification on the
existing piping system, it is not an expensive device and it
helps to reduce electricity bills.
Renewable: Powered by the water flow and water pressure in
order to generate electricity.
Sustainable: Power generated as long as the water flow within
the piping system. It helps to increase energy efficiency.
Green: Zero carbon emission and no waste. A step closer to
green the buildings.
Can be used at all types of building – as long
as the building has a water piping system
which is functioning.
Kinetic energy from induction
from Coils and wires.
With all the benefits stated.
The Competitor Analysis
• 2011, LUCID ENERGY from the USA has
patented an industrial liquid turbine.
The Competitor Analysis
Due to industrial liquid/municipal
water distribution, the turbine is large
in size, powerful to generate reliable
electricity for massive usage.
Large turbine, only suitable to be used
at industrial scale.
The energy generated is to power the
devices used for liquid and water
The piping layout is horizontal which
taps the mechanical force (generated
by pump) to power the liquid flow.
Therefore the energy efficiency is still