How often should the apartment water tank actually be cleaned in Dubai, and what should tank cleaning cost?

It is a genuine hygiene item here, not a racket, though the frequency people quote varies. In Dubai's heat a tank collects sediment at the bottom, can grow biofilm on the walls, and holds warm standing water, all of which make periodic cleaning worthwhile; the common sensible schedule is a proper clean once or twice a year, and sooner if you ever notice a change in taste, colour or smell, or if the tank is older or rarely turned over. A proper clean is not a quick rinse: it is draining the tank down, scrubbing out the sediment and any biofilm, disinfecting, then flushing and refilling, ideally with the tank inspected for cracks or a poor-fitting lid that lets dust or light in (light encourages growth). What drives the cost is mainly the tank size, how accessible it is, and how many tanks you have, not expensive materials. So a realistic approach is a scheduled once or twice-yearly clean, done properly, with an out-of-cycle clean if the water ever seems off. Booking water tank cleaning in Dubai on a set schedule, rather than only reacting when something tastes wrong, is the sensible way to run it in this climate. Getting the lid and any cracks sorted at the same time stops the tank getting dirty again fast.