28.11.2025 08:45
The Ministry of Environment, Urbanization and Climate Change announced that rainwater harvesting and gray water systems will be mandatory in large-scale private and public buildings starting from January 1, 2026. The regulation aims to save approximately 10 million cubic meters of water annually.
With a new regulation by the Ministry of Environment, Urbanization and Climate Change, rainwater harvesting and greywater usage will become mandatory for large buildings. Accordingly, permits will not be granted for certain types of private and public buildings without the installation of these systems starting from January 1, 2026.
RAINWATER SYSTEM WILL BE MANDATORY ON A LARGE SCALE
With the amendment made to the Planned Areas Zoning Regulation on March 11, structures with a storage volume exceeding 7 cubic meters, projects with parcels larger than 2,000 square meters, private buildings with a roof projection area exceeding 1,000 square meters, and all large public buildings will be required to install a rainwater system.
The ministry stated that this application will recover approximately 6.2 million cubic meters of water annually. It was noted that the treated rainwater will be used for garden irrigation and toilet cisterns.
GREYWATER SYSTEM MANDATORY IN TOURISM FACILITIES AND SHOPPING MALLS
According to the regulation, accommodation facilities with a bed capacity exceeding 200, shopping malls larger than 10,000 square meters, and public buildings over 30,000 square meters will also install a greywater system.
Greywater obtained from showers, bathtubs, and sinks will be treated and used only in toilet cisterns. This application aims to achieve an annual water saving of approximately 4 million cubic meters.
NEW REGULATIONS FOR STORAGE TANKS
Technical conditions regarding the location of storage tanks have also been determined. Accordingly, tanks will be placed underground in back and side gardens. For tanks to be placed in the front garden, a minimum distance of 2 meters from the road will be required.
The rainwater storage capacity will be designed to meet at least 6% of the collectable water amount based on the roof structure and the average rainfall of the province. Greywater tanks will be required to meet half of the water used in their connected cisterns.
SIMILAR SYSTEMS ARE COMMON IN THE WORLD
In many countries, rainwater and greywater systems have long been encouraged or made mandatory. Germany provides discounts on water bills for buildings using these systems. The UK offers tax advantages in the first year of implementation. Japan mandates the system for all buildings over 30,000 square meters. In New Delhi, rainwater systems are mandatory for all roofs larger than 100 square meters. In the USA, the system is used for various purposes in over 100,000 homes. Australia requires the installation of a rainwater system before issuing new housing permits. Singapore meets 5% of its urban water needs with treated rainwater.
In Turkey, the separate rainwater drainage system has started to be used in 7 of the 30 metropolitan cities. These cities include Ankara, Diyarbakır, Istanbul, and Kocaeli. It is also noted that many factories utilize collected rainwater for irrigation.