1. Requirements on materials and the selection
of materials to prevent contamination from
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
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
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
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
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
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
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
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.