3.1 Town communitiesThe supplier of water to most cities and towns is the state or territory water authority. Communities which are situated near towns usually get their water from the town water supply.
In these communities, the water is pumped from its source which is usually a dam or bore. The water is treated for possible contamination and is then stored in large tanks or reservoirs.
From these tanks or reservoirs a complex system of underground pipes takes the water to the community's houses, schools, hospitals and other users.
Fig. 6.21: Plan of large community water supply.
It is the supplier's responsibility to maintain the water supply equipment. Normally, this will be the water authority. The supplier usually looks after all pipelines to houses and other buildings. Maintenance and repair of water plumbing in the yard or house is the responsibility of the owner of the house.
3.2 Bush communitiesMost communities that are situated away from towns get their water supply from a bore. The bore is sunk in an area where the water is cleanest and most plentiful. Sometimes, water for a bush community is pumped from a river, pool or billabong.
The bush community’s water supply is a smaller version of a town water supply. When the water is pumped from the bore it is first treated to make it clean and free of germs. It is then pumped into a storage tank.
From the storage tank a network of pipes carries the water to the houses, the school, the clinic, the shop and any other buildings.
Fig. 6.22: Small community water supply.
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3.3 The elevated tankCommunity water tanks can be set on high stands or placed on a nearby hill. The reason is that the elevation (height) of the tank creates the water pressure at the tap.
The higher the tank above the taps in the community, the greater is the water pressure at the taps. The maximum (greatest) height for a community water tank is usually 12 metres.
Fig. 6.23: The higher the tank the greater the pressure.
If water pressure at the taps was not created by elevating the tank, the water from the taps and hoses would dribble out very slowly or no water would come out at all, for example, it might take an hour to fill the toilet cistern or it might be impossible to have a proper shower.
3.4 Pipe layouts in the communityWater pipes come in different widths. The width of a pipe is the measurement of its diameter. The diameter is the distance across the centre of the pipe. Some measurements are taken across the inside of the pipe, and others from the outside.
House plumbing is usually copper or sometimes PVC. Copper is always used to carry hot water. Other water supply pipes around a community are usually PVC.
The water pipes around houses are usually 12 mm pipes, although 18 mm or 25 mm pipes are sometimes used. Pipes of these sizes would be too small to bring the water from the storage tank to all the houses and other water users, such as the clinic and the shop. These pipes are much larger and are strong enough for the high water pressure. They are called main water pipes.
For a small community the main water pipe from the supply tank to the houses is usually a 50 mm PVC pipe. For larger communities a 100 mm PVC pipe is used and very occasionally, a 150 mm PVC pipe. The larger pipe is used when there are lots of houses to be serviced or when the water has to be transported over a long distance. This larger pipe gives a better flow so that the pressure is not lost at the tap.
To get water from the main pipe to houses and other places, smaller branch pipes are taken from the main pipe. The main pipe will get smaller in size as the branch pipes are taken from it. This maintains the pressure to the water users regardless of their distance from the tank.
Depending on the community layout, individual water users will obtain their water service from the branch pipes or sometimes in small communities, directly from the main pipe. Pipes used to take the water from the main into the houses and other buildings are usually 18 mm PVC.
At several points along main pipes there are taps (or valves) which allow the water to be turned off. One of these taps is at the tank so that the whole community’s water supply can be shut off if necessary.
Other taps are usually placed where branch pipes go off from the main. This is done so that only one branch needs to be shut off if a break occurs or if some maintenance work needs to be done.
Fig 6.24: Plan of community water supply showing cut-off taps.
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The government water authority has plans of the water supply system for most communities. These plans can be obtained through the community office.
It is wise for each community to try and get a copy of the plan of its own water supply system. This will help the EHP and/or other people to find all the underground pipes and the cut-off taps in the system.
Each house or building supplied with water has its own main cut-off tap. This tap is set in the pipe coming into the house from the main or branch water pipe. It is normally located in the ground not far in from the fence line of the house. If this tap is turned off, all the water to the house is stopped. Each householder should know where to find the main cut-off tap.
Fig. 6.25: House cut-off tap.