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DUWLs
6.80 No currently available single method or device will
completely eliminate biocontamination of DUWLs
or exclude the risk of cross-infection. To reduce
contamination risk, a combination of methods is
applicable (see also Section 3).
6.81 With regard to Legionella and other water-borne
pathogenic agents, the HCAI Code of Practice
(2009) states:
“ Premises should be regularly reviewed for potential
sources of infection and a programme should be
prepared to minimise any risks. Priority should be
given to patient areas although the exact priority will
depend on local circumstances”.
6.82 Guidance from L8 advises that at-risk systems,
particularly those used with the patient, be drained
down at least at the end of each working day.
Where manufacturers provide protocols for daily
cleaning, these should be applied.
6.83 Self-contained water bottles (bottled water system)
should be removed, flushed with distilled or RO
water and left open to the air for drying overnight.
They should be stored inverted.
6.84 Where visual contamination is present, flushing
with a suitable disinfectant followed by thorough
washing is necessary. The manufacturer’s
instructions will specify the disinfectant to be used
and may also require the continuous presence of
antimicrobial agents to prevent the build-up of
biofilms.
Note
The self-contained water supplies used with dental care
systems should be freshly distilled or RO water (see
Section 3). Certain systems recycle water back to a
storage facility. Where this is done, repurification will
be necessary at each cycle.
If self-contained water bottles are not used, a Type A
air gap should separate the DUWLs from the mains
water supply. Such arrangements should be subject to
consideration of local water quality, particularly where
hard water is used.
6.85 DUWLs should be flushed for at least two minutes
at the beginning and end of the day and after any
significant period when they have not been used
(for example, after lunch breaks). In addition, they
should also be flushed for at least 20–30 seconds
between patients. Whilst these actions have been
shown to have only a small effect on biofilm build
up within the DUWL system, they do usefully
reduce microbiological counts in the water delivery
tube during the period when patients are likely to
be exposed. Some water-purification systems are
capable of supplying DUWLs and may be able to
reduce microbiological risks.
Note
Care should be taken to minimise the occurrence of
splashing and aerosol formation.
6.86 Disinfection of DUWLs should be carried out
periodically. In all cases, the manufacturer’s
instructions should be consulted. Sodium
hypochlorite and isopropanol and a number of
other agents have been shown to be effective in
the removal of biofilm as well as the reduction of
microbacterial contamination. However, these
agents should only be used where recommended
by manufacturers. If they are used, care should
be taken to ensure that DUWLs are thoroughly
flushed after disinfection and before being returned
to clinical use.
Notes
(1) There is disagreement within the scientific
literature concerning the effectiveness of waterbased
flushing of DUWLs, particularly in respect
of biofilm control. For systems making use of
potable water (that is, where the water supply is
drawn from a mains water system), the nature of
the building’s water-supply arrangements may be
an important consideration. This is particularly
so where storage tanks are used. Where delivered
water quality is in doubt, dental practices should
consider adopting continuous dosing systems
if permitted by the DUWL manufacturer’s
recommendations. If dosing is used, it is important
to ensure that the dose rates delivered are within
the recommended safe limits for the product used.
Dental practices that use a potable water option –
through air-gap supply or the use of bottles –
should consult with their appointed Competent
Person in respect of local water quality and
suitability.
(2) For those using purified water, such as freshly
distilled or RO, possibly with UV treatment, the
rate of biofilm build-up is likely to be low, provided
that water lines are regularly disinfected and
maintained.
(3) Particular caution should be taken with regard
to dental handpieces where dosing is applied, as a
number of instances of damage have been reported.
6.87 Dental equipment requiring protection against
backflow should have anti-retraction valves
incorporated on all handpieces, ultrasonic scalers
and/or water lines (see Section 3). Responsible
persons should ensure these are fitted where
required. They must be regularly monitored and
maintained.
6.88 Examples of dental equipment requiring backflow
protection are:
• dental spittoons;
• three-in-one syringes;
• wet-line suction apparatus; and
• self-filling automatic radiographic processors
(where still used).
Adherence to the equipment manufacturer’s
recommended cleaning procedures, including the use
of the manufacturer’s recommended chemicals, is a
requirement for medical devices such as those listed
above.
6.89 Where in-line filters are used, these will require
treatment using an appropriate cleansing solution
at intervals recommended by the manufacturer –
but always at the end of each session. This step
should be performed after first flushing the
DUWL.
6.90 If the DUWL has disposable filters, they should be
replaced daily.
See Section 3 for further guidance on DUWLs.
6.91 For dental surgical procedures, surgical flaps
or other access into body cavities involving
irrigation, the use of sterile water or sterile
isotonic saline provided from a separate single use
source is recommended
