Water Waiting

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. 

1. As the sun shines, water from the bottom of the hot water tank is drawn into the bottom of the solar heating panel.
2. The water heated in the solar collector rises and flows into the top of the hot water tank
3. 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.