In some parts of the world, houses received a constant
supply of pressure – in areas of the world with few water resources, the water
is typically delivered periodically, and to only certain parts of the city at
one time - and it is up to the customers to maintain storage capacity to keep
them supplied through the dry periods.
Above the street on the roofs of almost all the buildings of
Ramallah are hundreds of water tanks. The tanks serve to store the drinking
water which is delivered to houses in Ramallah only two or three days per week.
In the older centre of town the tanks have been added in a haphazard way by
individual apartment owners over the years.
On the newer buildings, all the tanks are installed in neat
orderly rows
Since water is only sent through the City distribution
system a couple times per week, less water is lost through leaks in the City
Network – than if the entire network were constantly pressurized. The water is
still metered however as it enters each property.
If the tanks are not regularly cleaned and dis-infected, and
if they are not isolated from the atmosphere with air filters and securely
fastened lids – the water can become contaminated.with micro-organisms.
The water tanks are also typically combined with solar water
heaters. In the photo below - The cold stored water is in the black tank at a
higher elevation – it provides the constant pressure to the combined insulated
tank and solar heater.
- As the sun shines, water from the bottom of the hot water
tank is drawn into the bottom of the solar heating panel.
- The water heated in
the solar collector rises and flows into the top of the hot water tank
- Which pushes water from the bottom of the hot
water tank – into the bottom of the
solar heater.
In this way, during
the day the water slowly moves in a loop between the solar collector and the
hot water tank - steadily increasing the water temperature in the insulated
tank.
When the day ends, and the sunshine ends, the water in the
solar collector will no longer be hot enough to displace the water in the
insulated tank and the circulation automatically stops. The water heated during
the day is then piped from the top of
the hot water tank into the house – and cooler water flows into the bottom of
the hot water tank from the main water supply tank.
Although these are simple, effective systems – they are rare
in countries with low-cost energy – such as Egypt
– because electric water heaters have a lower initial cost.
