by Ancien_Opus » Mon 12 Dec 2005, 12:16:45
Water towers do not normally freeze, especially if they're the correct size.
This is the same concept that water flowing in a river does not freeze, with a little geothermal consideration. Superficial surface ice does form in the elevated tank. Typical water towers are turned over in 24 hours, many are turned over in less time. This means the entire volume of water is exchanged with the users. The water coming into the tower from groundwater is about 50 degrees F and contains a great deal of heat compared to ambient air temperature that may be say -2 degrees F. It will lose some heat to the tower but will regain heat underground during transmission to the homes. The same 50 degree water will feel cool in the heat of summer, even though it was stored above ground as well. Think of this as a collosal heat pump, which could fail if the water stops moving.
A water tower is a form of providing constant pressure to a water system by gravity. The water pump can be run a short amount of time to lift the water into the reservoir when it is needed. Otherwise a pump would have
to run continually either pumping water or air (hydropneumatic systems) to keep water pressure constant in the system. There are variable pressure water pump demand systems in use but they are not very common.
Moving water requires energy. The basic construct of that energy source matters a great deal in light of peak oil. The infrastructure is usually dependent upon transporting and excavating which are largely dependent upon liquid fuels. Considering the most basic components steel, ductile iron, cement or plastic pipes the impact of peak oil will be significant. Most water utilities use electricity to provide the main source of energy for water supply.
Regards,