AEG F99009M0P - Manual (Page 26)

If you connect the water drain hose to a trap spi-
got under the sink, remove the plastic membrane
(A). If you do not remove the membrane, remain-
ing food can cause a blockage in the drain hose
spigot
A safety device impedes the dirty water to go back
into the appliance. If, the spigot of the sink has a
'non-return valve', this can cause the appliance to
drain incorrectly. Remove the non-return valve.
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