If the tap water is suspected to contain harmful bacteria, viruses or parasites, the municipality may issue a recommendation to boil the water. In that case, water used for drinking or cooking should first be brought to a heavy, rolling boil.
In case of a shortage of potable water, the municipality may deploy water tanks, so-called emergency water. There may also be pre-assigned tap sites where you can fetch water. Contact your municipality to find out where these sites are located. Bring your own vessels to fill up.
During large-scale power outages that may occur after storms, for instance, running tap water may stop working. So whenever storm warnings are issued, it is advisable to store water in advance.