Dual Water Distribution
Dual water distribution is a technology facilitating water supply. In this system, water from two different sources are supplied into two separate distribution networks. The two distribution system works independently of each other but works witin the same service area. In dual distribution systems, usually potable water is supplied through one distribution network and non-potable water through the other. This system is used in mainly to distribute inadequately treated water into public areas for purposes like fire-fighting, sanitary flushing, street cleaning or irrigation of ornamental gardens or lawns. This system is popular in some Caribbean islands like Saint Lucia and the U.S. Virgin Islands.
Technical Description of Dual Water Distribution
Typically, a dual water distribution system comprises two separate distribution pipe networks. One pipe is used as an outlet to the potable water distributing system, and the another pipe is used for distributing sea water or other non-potable waters. Apart from distribution pipes, the system also includes valves, hydrants, standpipes and a pumping system, if required. Generally, pumps are used in seawater-supplied systems, where the water is lifted to higher elevation storage tanks. Likewise, pumps may be required to lift wastewaters from wastewater sumps or other collection points. The pumping system of a dual water distribution system comprises the following:
- A pumping station containing the water intake
- A pumping well
- An elevated storage tank for emergency use.
- Foot valves, or one-way valves, in order to retain their charge of water.
The potable or primary section of dual water distribution system, like any other potable water supply and distribution system, requires: a water source, treatment plant, storage facility and distribution system. Pumps are used to lift the potable water from the treatment plant to the storage tanks; from there the water is distributed by gravity to the point of use.
Suitability of the Dual Water Distribution
This system can be best used in areas near the coast where seawater is abundant, or in places where wastewater is readily available as a source of supply. Whereas, it can also be used in areas that have rivers, streams, or other water sources but lack treatment facilities.
Advantages of Dual Water Distribution
Various expensive and limited potable water supplies are used in to provide water for various non-consumptive purposes like fire extinguishing, sanitary flushing etc. Using dual water distribution system cheaper sources of water can be utilized for such non-consumptive purposes.
This technology can make more potable water available to the general public, if incorporated into the regular distribution system.
Disadvantages
- It costs double expenditure as two distribution systems have to be installed.
- This system allows the use of untreated seawater or wastewater to irrigate leafy vegetables, which can make this vegetables not so apt for consumption.
- The transport of seawater through the pipes can prove to be highly corrosive to metal pipes, fittings, and appurtenances; and thereby increasing the maintenance cost.
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is continually depleting with its increasing demand. Key reasons that account for the growing demand of water.