A domestic waterworks serves as a water supply system for buildings that are not connected to the public water supply. It supplies residents with industrial and drinking water. But a waterworks can also be used despite the connection to the public water supply in order to save water costs. 

In many cases, the expensive tap water can be replaced by free well water or rainwater, e.g. for

• Irrigation for the garden
• Supply of showers and other sanitary facilities
• Operation of the washing machine
• Drinking water (with appropriate water quality)

 

 

 

How a domestic water pump works

A domestic waterworks works by pumping the water from a reservoir into a network of pipes so that it is available to the user at constant pressure. The reservoir can be a well, spring, cistern or water body. If drinking water is also to be withdrawn, an external tank is often installed.

 

The components

The pump is usually an underfloor or. submersible pumps and used because they are characterized by low operating costs, low noise pollution and higher efficiency.

Overfloor pumps can also be used; they are cheaper to purchase, but require a lot of maintenance and can only be used with a maximum delivery depth of 7 meters.

To prevent the pump from running dry, electrodes are placed in the reservoir to check the water level and switch off the pump if necessary. When the pump is switched off, a backflow preventer prevents water from flowing from the pressure line back into the reservoir.

 

The pressure

The pressure in the pipe network must be maintained, even if the water is taken from the users. To ensure that the pump does not have to be started up too frequently and that the entire system does not suffer any pressure surges, a pressure tank is used above a certain size in domestic waterworks. This is filled with gas, which is compressed by the incoming water up to a preset maximum value. If this value is reached, the pump is switched off. If water is removed by the user, the pressure in the pipe network drops and the gas expands again. When a minimum pressure is reached, the pump is switched on again. The switching operations are controlled by a pressure switch. Small systems are usually operated without pressure vessels. Only pressure and flow monitors are used here.

 

Domestic waterworks or domestic water automat

The difference between a domestic waterworks and a domestic water automat lies in the way it handles the line pressure.

As already explained in the above paragraph, water in a domestic waterworks is stored in a pressure tank and a pressure switch keeps the pressure in this tank at a level between switch-on and switch-off pressure.

With a house water automat the pump switches on immediately, if the pressure in the line decreases, i.e. a tapping point is opened. If the tapping point is closed again, the pump control registers this and switches the pump off after a short run. The after-run is important to prevent the pump from constantly switching on and off during small water withdrawals, e.g. for a toilet flush or also during a leak.

A domestic water automat is used when a constant pressure is required, e.g. for garden irrigation. (In this case, a domestic water automat switches on when the water is drawn, in contrast to a garden pump which is switched on manually).

A domestic waterworks is advantageous if no constant pressure is required and even small amounts of water are removed, e.g. to operate a washing machine or flush a toilet. In these cases, an immediate switching on of the pump is disadvantageous because of the noises and also because of the current consumption.