Water tanks: the plumbing job people forget is a hygiene regulation
Almost every UAE building stores water in rooftop or ground-level tanks, and utilities such as DEWA, ADDC and SEWA are responsible for quality only up to your meter — everything after that, including the tank, is the owner's responsibility. In summer, a poorly sealed tank at 45 degrees ambient is an incubator, which is why municipalities publish tank cleaning guidance and why Dubai Municipality registers the companies allowed to do the work commercially. A sensible rhythm for a villa is a professional clean and disinfection every six to twelve months; in an apartment building, the owners association should hold the certificates and produce them on request.
Tank hygiene and plumbing intersect constantly: sediment from a neglected tank is what blocks mixer cartridges, jams float valves and accelerates scale in heaters. If your cold water runs cloudy after a windy week, or you are booking a plumber for a third gritty-aerator complaint, mention the pattern in the booking notes — a good technician will recognise tank sediment as the root cause and tell you to escalate to the building rather than sell you another mixer.