Domestic water supply systems from KSB: water supply the independent way

Domestic water supply system – cost-effective and popular

In many locations, a domestic water supply system can replace expensive tap water from the water supply network by rainwater, service water and groundwater. The system is quiet, cost-efficient and, most importantly, independent from the public water supply.

An example of where a domestic water supply system can be used is a toilet cistern. Flushing the toilet works just as well with free rainwater than with tap water. The same applies to washing machines. Rainwater is actually easier on the machine, as it contains clearly less lime than tap water.

A domestic water supply system is also suitable for:

• Irrigating gardens
• Operating irrigation systems
• Supplying showers and other sanitary appliances with water

Benefits of a domestic water supply system with a centrifugal pump by KSB

• Noticeably less water consumption from the public water supply network lowers household costs
• Cost-efficient and used in buildings without connection to the public water supply
• Versatile (also for use on commercial premises) and more than a cost-saving alternative for owner-occupied houses

The right pump for your domestic water supply system

For transporting water in a domestic water supply system single-stage or multistage centrifugal pumps are used, depending on the pressure requirements. Underfloor or submersible pumps are ideal because they have got lower operating costs, higher efficiencies and a lower noise emission.

These pumps are protected against dry running by electrodes attached in the reservoir, which monitor the water level. If the water level is too low, the electrodes cause the pump to stop. A check valve ensures that no water flows back from the discharge line into the reservoir when the pump is stopped. If a domestic water supply system is fitted with a centrifugal pump, it is self-priming, corrosion-resistant and provides a high hydraulic performance – ideal conditions for use in the garden and house.

Another option is installing a domestic water supply system with a submersible pump. In this case, the domestic water supply system will be fitted with a multistage submersible pressure pump with a high pressure, which is also well-suited for use in the garden and house. The advantages of a domestic water supply system with a submersible pump: It can be used immediately – without lengthy venting of the pipes – and does not cause much noise in the house.

A domestic water supply system can also be fitted with above-floor pumps. These pumps are usually less expensive to procure but their large maintenance effort increases the operating costs to such an extent that they are less cost-efficient than underfloor or submersible pumps. Also, they can only be used for depths of up to seven metres as, otherwise, the maximum attainable suction lift would be exceeded.

Domestic water supply systems in a nutshell

This is how domestic water supply systems work

The water is taken from a reservoir, for example for supplying toilets and washing machines with water that is not drinking water. Suitable reservoirs are wells, bodies of water or cisterns. The water is pumped from the reservoir into a piping system.

A domestic water supply system essentially comprises the following components:

• Reservoir
• Pump or pumps
• Accumulator – usually a hydrophor or a membrane-type accumulator
• Pressure gauge
• Safety valve

A domestic water supply system is usually selected for pumping from a depth of about nine metres. The head is between 40 and 50 metres. Depending on the pressure requirement, a single-stage or a multistage pump will be used.

Purchasing a domestic water supply system: What to be aware of

For selecting the right domestic water supply system a high-quality, high-efficiency pump is paramount. The pump should consume little energy and have a low noise level. These requirements are best met by multistage piston or centrifugal pumps. A domestic water supply system with a centrifugal pump comprises a multistage centrifugal pump whose output is ideal for garden and house water applications.

A domestic water supply system with a submersible pump is fitted with a multistage submersible pressure pump with a high pressure, which is also well-suited for use in the garden and house. The advantages are that this domestic water supply system can be used immediately without lengthy venting of the pipes and that it does not cause much noise in the house. The domestic water supply system can be combined with a pump control system to automatically open and close a consumer installation.

Differences also exist between domestic water supply systems and automatic domestic water pumps. Automatic domestic water pumps are suitable for handling clean water from wells and cisterns, for service water or rainwater harvesting, for irrigating gardens and for operating irrigation systems. The water pumped can be transported under pressure and used as if it were tap water. This convenience is usually enabled by an electronic control system with a defined start-up pressure. The start-up pressure cannot be changed; for most models it is 1.5 bar.

Automatic domestic water pumps are versatile in use. However, they quickly reach their limits – for example in the domestic water supply with service water or rainwater. Although automatic domestic water pumps can be used for this application to some extent, it is not recommended because neither the start-up pressure nor the stop pressure can be defined by the user. This is why automatic domestic water pumps are not suitable as pressure booster systems either. For such applications, using a domestic water supply system is the recommended option.