Water
İSKİ (Istanbul)Register in your name once you have your lease and ID documents; billed monthly.
Electricity
CK Boğaziçi (European side) / Enerjisa (Asian side)Provider depends on which side of the Bosphorus your apartment is on.
Gas (doğalgaz)
İGDAŞHeating bills roughly double during winter months (Dec-Mar) — factor this into your budget.
Internet (fiber)
TurkNet, Superonline, or Türk TelekomInstallation typically takes a few days to two weeks depending on whether the building is already wired.
Mobile
Turkcell, Vodafone, or Türk TelekomRemember the 120-day foreign-SIM rule if using your own phone long-term.