'Su terazi' in Turkish. Siphon used to balance the pressure along the supply line. It worked like an inverted siphon: the pipe running up discharged into the water tank while the water decanted again into the conduit going down and this was repeated in sequences to the next tower until the water reached its destination (Kessener, 2017, p. 90, for further technical explanation, see Ibidem, p. 91-95). The water towers have been into well into the early 20th century, as Abdulhamid II completed the Hamediye water line. It is not known how long the suterazi kept functioning after this completion (Kessener, 2017, p. 106).
Byzantine period
Evidence for water towers in the Byzantine period is rather flimsly. A note in Crows work (2012) explores the possibility whether John Skylitzes' kastellos may refer to a water tower, a Byzantine equivalent of the later Ottoman suterazi. However, the meaning of kastellos remains too ambiguous, and according to Kessener, 2017, p. 86-87 it is more preferable to indentify these as castellum or public cistern. Only the remains of one possible water tower survive west of Antalya, however this specimen lacks a water tank on top of it. See for the discussion of "Byzantine" water towers Kessener, 2017, p. 87-88.
Ottoman period
It therefore remains unclear whether the suterazi was independently developed by the Ottomans, or whether they were preceded by a Byzantine version. They are however already depicted on Ottoman water maps (now in the Topkapı Museum), the oldest dating from 1584 and 1607. These water towers could either be repaired Byzantine ones, or newly built Ottoman ones. The Ottoman water infrastructure was mapped by Count Andreossy between 1812-1814 in his Book III of Constantinople et le Bosphore de Thrace (1828). It describes that the Ottoman water transport system consisted of piped conduits (lead or ceramic), running at or below ground level, and that at certain intervals it went up and down through a water tower with a water tank on top (Kessener, 2017, p. 89-90).