•  

Basic requirements for hygiene-conscious planning

The detailed requirements arising from the technical criteria can be summarised in a small number of protection targets. Below, you will find notes on each of the protection targets with due regard to the requirements of the healthcare sector:
1. Requirements on materials and the selection of materials to prevent contamination from chemicals substances
Pipe systems, fixtures and faucets largely consist of metal. The inevitable contact of drinking water with inside metal surfaces leads to reactions governed by the laws of nature and may therefore cause an increase in the concentration of metal ions in drinking water. By minimising alloy components that would impact the drinking water and by adjusting materials to drinking water quality under either DIN 1988-7 or DIN 50930-6, GROHE ensures that its products meet these high standards.

2. Requirements on materials and on the selection of materials for the limitation of microbe colonies
Seen under hygienic aspects, non-metallic materials are particularly important in this context, as they may encourage the formation of biofilms in water supply systems. The requirements on such materials have been specified in the UBA Guideline on the Implementation of KTW (the German Testing Guideline for Organic Materials), supplemented by the requirements in DVGW info sheet no. W 270. According to the German industry standard DIN 1988-2, products may only be installed for drinking water purposes if they comply with the established technical criteria. This is not an issue for GROHE.

3. Dimensions of supply systems -- avoidance of excessively long periods of stagnancy and of germination
„Water must flow“ -- even the Romans knew this. For modern water supply systems it means above all that pipes need to have suitable dimensions for their purpose, taking account of the conditions of simultaneousness (DIN 1988-3) which occur in the healthcare sector. It means that planners have a special responsibility when determining the simultaneousness factors.

4. Securing connected machinery and appliances

If machinery is integrated into water supply systems (machinery such as heat exchangers, drinking water heaters, water treatment units) or if appliances are connected (such as washing machines, dishwashers and cleaning machines), then they must be secured primarily under DIN / EN 1717 and under the German standard DIN 1988-4, which is currently still valid. Depending on the hazard category of a given appliance, a safety device must be added. If therelevant machinery or appliance bears a DVGW certification label, then it is considered to be intrinsically safe and can be connected without the need for further measures.

5. Prevention of backflow

A drinking water supply system terminates at the exposed taps at the points of use or at the relevant safety taps as specified in DIN / EN 1717. In the case of bathroom fittings with hand or fixed shower attachments there is the danger of point-of-use backflow. Safety devices integrated into taps serve to protect the drinking water against such hazard, making GROHE taps intrinsically safe.

6. Anticorrosion requirements
Drinking water supply systems may suffer not only interior corrosion, but also contact corrosion, the formation of elements and exterior corrosion. DIN 1988-7 lays out the different types of corrosion and specified measures to ensure that planning and implementation meet anticorrosion requirements. Planning a drinking water supply system Standards and guidelines.

7. Prevention of leaks and of the intrusion of contaminants

Once completed, an installed pipe system must be given a pressure test under the ZVSHK procedure sheet. For hygienic and practical reasons, pressure testing should be conducted with either air or inert gas. If water is used for pressure testing, then the system must be started up immediately after the test, to ensure regular water renewal through flushing schedules. While laying pipes, it is important to ensure that no impurities can get into the system through any of the apertures.

8. Prevention of stagnant areas

Stagnant water in pipes has a detrimental effect on the quality of the drinking water and must be viewed in similar terms as exceeding the use-by date of a food item. The German industry standards DIN 1988-2 and DIN 1988-4 therefore specify that water must not remain stagnant during planning, construction or operation. Bypasses without any flow are not permitted.

9. Flushing and, where appropriate, disinfection of drinking water supply systems upon start-up

Drinking water supply systems must be thoroughly flushed upon start-up. The ZVSHK procedure sheet „Flushing, Disinfecting and Start-up of Drinking Water Supply Systems“ specifies the different flushing methods (water or water/air, pulsatory) and when they are required. Flushing must always involve the use of filtered drinking water. To prevent the occurrence of pollutants, domestic systems that have been stagnant for a long time must be flushed thoroughly in coordination with the relevant water utility before the supply system is filled again.

10. Regular inspection of systems
Like all other technical systems, drinking water supply systems must be inspected at regular intervals under DIN 1988-8 and must be given appropriate maintenance. VDI 6023 sheet 1 provides a wide range of answers to questions on inspection and maintenance and contains a number of checklists.

11. Disconnection of whole systems and parts of systems that are no longer in uset
Pipes and systems that are no longer used for their intended purpose and which are therefore stagnating must be disconnected. Until this has happened, they continue to be part of the drinking water supply system and must therefore be flushed regularly.

12. Requirements on water treatment systems (filters, metering devices, ion exchangers) designed to prevent germination and to ensure observance of limits for chemical substances
All water treatment systems must meet the requirements of DIN 1988-2 and be correctly dimensioned. Any systems that differ from those specified above -- e.g. chlorine dioxide systems installed as precautions -- do not meet the purity requirements of the German Drinking Water Regulation. If substances are added to the drinking water, then users must be notified.

13. Requirements concerning inadmissible heating of cold drinking water
Under the German Drinking Water Regulation, cold water must have a temperature of no more than 25 °C. When planning and building cold water supply pipes, it is therefore important to ensure that there are no inadmissible increases in temperature. According to VDI 6023 sheet 1 any pipe systems with warm or hot water must be fed through different shafts and ducts. If water pipes for cold drinking water are situated next to warm or hot pipes in a given slot, then DIN 1988-2 stipulates that they must be given the same insulation as pipes in heated rooms.

14. Prevention of wet fire extinction pipes as potential sources of contamination

If wet fire extinction systems are connected directly to the drinking water supply system, then this creates hygiene risks which cannot be controlled. Fire extinction and fire proofing systems are rarely used for their intended purpose. All planning, construction and operation must therefore ensure either that water does not turn stagnant or that it is kept away from the drinking water system with absolute certainty. Since the publication of the German industry standard DIN 14462 it has no longer been possible to connect type F wall hydrants directly to drinking water supply systems. Fire extinction and fire protection systems must either be connected indirectly or set up as dry/wet systems. Moreover, the new draft DIN 1988- 60 contains even more stringent requirements on drinking water hygiene. The aim is to separate drinking water and fire extinction systems from each other through a multi-barrier system wherever this is possible.

15. Hot water temperatures above 60 °C to reduce legionella growth

DVGW info sheet no. W 551 describes measures for the prevention of legionella growth in drinking water heating and supply systems. The best way to warrant perfect drinking water is to observe a storage temperature above 60 °C at all times and to ensure that the pipe network is calculated and hydraulically synchronised in accordance with DVGW info sheet no. W 553. Good circulation right up to the last tap on the top floor brings not only hygienic benefits but also user convenience. European DIN EN 806-2 standard expressly points out that mechanical mixers (i.e. mixers without thermostats) supplied with hot and cold water from different pipe systems represent a risk of scalding if one of the supply pipes fails or if there is a pressure drop in the cold water line.
Consequently, installations for heated drinking water have to be planned with a view to minimising the risk of scalding. This is why water outlets in the healthcare sector have to be fitted with thermostat mixers permitting to set a maximum temperature limit. This upper limit is 43°C in hospitals and 38°C in special areas of care homes. GROHE thermostatic taps ensure that users do not scald themselves. 

DIN EN 806-2 also requires protection against hot surfaces. To rule out the risk of users hurting themselves when touching exposed parts of a drinking water installation, the surface temperatures of the latter should not exceed the temperature of the dispensed water, i.e. 38°C or 43°C respectively. The GROHE CoolTouch® technology ensures that GROHE thermostats meet this requirement. According to the DVGW Work Sheet W 551, installations for heating drinking water have to be planned in a way which permits to heat the contents of the storage tank to 75°C within a short time. This is required to perform thermal disinfection cycles at short notice. To ensure effective thermal disinfection, the water temperature needs to be at least 75°C at the outlet point for three minutes. A particularly easy unlocking mechanism on the Grohtherm 2000 Special makes it easy to perform thermal disinfections in next to no time.