Does Istanbul Have Water Security (Drought, Tap Water Quality, Earthquake Preparedness, etc.)?

Water quality and safety in Istanbul

The inoperability of the Melen Dam due to cracks in its body has upset Istanbul's water supply plan and created a water supply security risk. ISKI is trying to supply this water from Melen Stream with three large pumping stations. However, since the flow rate of Melen Stream is low during the summer months, sufficient water cannot be taken. For this reason, this water is also pumped into Ömerli dam during the rainy season and this dam is also used as an interim storage for dry periods.

On the European side, where 65% of Istanbul's population lives, 30% of the water resources are located. Therefore, the demand is high. This jeopardises the security of the quantity of water to be supplied to this region in case the coming months are dry. Apart from this, we do not have any data to claim that Istanbul tap water is unhealthy and unsafe in terms of quality.

These waters are controlled by several institutions by taking continuous samples from thousands of points. For this reason, it can be said that the use of tap water will not pose a danger to human health unless unusual conditions occur that will cause local and local contamination of the water.

Is a purifier necessary to use tap water? 

The water supplied by ISKI comes to the entrance of the apartment buildings in normal times, i.e. in periods when there are no problems such as sudden city floods, etc. in a quality that meets the drinking and potable water standards. Then, it reaches the fountains of the households in the same quality in proportion to the cleanliness of the water tanks of the apartment buildings. This water is controlled every day by both ISKI and the Provincial Health Directorate with samples taken from thousands of points. However, in order for this water to reach the end user in a healthy way, it needs to be chlorinated frequently. This allows water users to regulate the taste and odour of the water by using a water purifier in their fountains. The use of these purifiers is also common in many EU countries. There are great advances in technology in this field. This makes the use of these devices widespread.

Ultimately, local governments need to make their public service understanding more efficient in order to provide healthy and potable water at the most affordable price or even free of charge up to a certain amount. Once the water administrations of the municipalities provide this, it is not an obligation for consumers to use water purifiers at fountains, but a preference, which is a normal behaviour.

As I have mentioned before, it is constantly announced by ISKI that tap water in Istanbul is of potable quality. So far, there has been no evidence to the contrary in the water brought to the entrance of the apartment block. However, quality control in water should be carried out meticulously and in a dynamic and widespread manner according to changing conditions. This data must be reliable and transparent. In addition, all statements to be made on water should be free from speculation. Because water is a vital resource whose demand is continuous and cannot be replaced by anything else. Healthy and continuous water supply is directly related to public health. Therefore, water administrations act with this awareness. In addition, it is necessary to be very careful when talking about the quality level of the water supplied. 

It is the most natural right of water users to have uninterrupted access to tap water in accordance with TSE drinking and potable water standards. The water management in Istanbul should seek an optimum technical and economic solution to increase the preference for tap water. 

In addition, it is also an understandable and appropriate choice for households to make this water more suitable for drinking in terms of taste, odour and mineral additives by using technological facilities with tap water purification devices. 

The use of purification devices in fountains for the use of tap water as drinking water in Istanbul is not because tap water is unhealthy, but because of the user's preference for water quality.

Drought in Turkey and Istanbul 

Turkey is a regional drought country, most of which is located in the semi-arid climate zone. The recurrence and severity of these regional droughts are increasing. Thrace is one of our regions that experience this drought frequently. The drought in Thrace directly affects the water supply security of Istanbul. 65 per cent of Istanbul's population is on the Thrace side and only 30 per cent of its water resources are on this side. Long-term meteorological data show that less precipitation falls on the Thrace side of Istanbul compared to the Anatolian side. Since water consumption is also higher, in a dry period, the smaller capacity dams of the Thrace region are emptied first. Therefore, we can say that the water security of the Thrace side of Istanbul directly depends on the water resources of the Anatolian side. Climatologists and meteorologists suggest that dry periods will be more frequent and severe in Thrace and Istanbul, as well as in regions such as the Aegean, Central Anatolia, Mediterranean and Southeastern Anatolia. Climate models also point to this. 

The actions to be taken in this regard are clearly and in detail in provincial disaster risk reduction plans, agricultural provincial drought plans and basin drought management plans. What needs to be done is to create an institutional capacity at the basin scale to implement these plans in order to prepare water management for drought or flood with an integrated approach at the basin scale. For this purpose, it will be beneficial to enact the draft Water Law as soon as possible and these management structures will reach the legal framework. However, preparations for the creation of this institutional capacity that will work effectively at basin scale should be started now. Along with this structure, capacity development should also be made in other institutions that will work in coordination at basin scale in all kinds of disaster management. It should not be too late for the plans to be put into practice effectively with a participatory management approach.

Are the dams in Istanbul ready for a possible big Marmara earthquake?

During the severe earthquakes centred in Kahramanmaraş, partial problems were detected in many of our dams. However, in some of these provinces, water supply distribution network and sewerage lines were damaged much more severely.

Istanbul's water supply is provided by 9 dams and 9 regulators. These facilities are spread over the water collection basins on the European and Anatolian sides. Due to their different locations, they are located at different distances from the fault line of the expected earthquake and on different ground properties. Therefore, they are expected to be affected differently by the probable Istanbul earthquake. The maximum earthquake accelerations that will affect the dams and the earthquake forces that will be generated by this will also be different.

Some of the Istanbul dams were constructed under the control of DSI Istanbul Regional Directorate and some were constructed by ISKI General Directorate. The earthquake resistance design criteria of these dams were determined by taking into consideration the seismicity of Istanbul and the regions where the dams are located and other effects. The projects and constructions of the dams were also realised accordingly.  

Of course, dams in Istanbul may be affected by an earthquake in the Marmara Sea and earthquake waves just like any other structure. However, the criteria applied in dam design and construction in Turkey so far have prevented serious damage to our dams. These criteria have also been applied to the dams in Istanbul. However, as the scientific studies on the magnitude and intensity of the expected earthquake in Istanbul have increased, it has come to the agenda to examine the earthquake resistance of some dams in Istanbul and to strengthen them when necessary. 

In this context, ISKI has initiated the "Project for Determining the Effects of a Possible Earthquake on Dams Supplying Water to Istanbul". Within the scope of this project, earthquake and flood risk analyses of all dams supplying water to Istanbul have been carried out; in the light of the outputs of the project, 'Additional Protocol for Rehabilitation Project Construction Works of Istanbul Büyükçekmece, Alibeyköy and Ömerli Dams' has been signed between ISKI and DSİ in order to carry out the necessary rehabilitation projects in the dams under the responsibility of State Hydraulic Works (DSİ).

In order to prepare rehabilitation projects for other dams under the responsibility of ISKI (Elmalı, Istranca and Terkos Dams), an appropriation has been included in the 2023 Investment Programme and project works have started. 

It can be said that the dams on the European side of Istanbul will feel the effects of the earthquake more strongly and may be affected more. 

In this context, 4 dams constructed and operated by DSİ and 4 dams constructed and operated by ISKI have been examined for their earthquake resistance and strengthening works have been started. 

Will there be a water problem in Istanbul after the earthquake?

After the earthquake, problems are encountered in water supply and wastewater disposal as a result of the unavailability of water supply and sewerage systems. If a solution is not found to this urgent water supply and wastewater disposal problem in a short time, the burden brought by the earthquake disaster becomes heavier and the loss of life increases. As the Water Policy Association, we published the "Earthquake and Water Report" on this issue in 2019. In the report, we also addressed the post-earthquake water supply risks of Istanbul.

The effects of the expected Marmara Earthquake on Istanbul's water supply and sewerage system have been determined through risk analysis studies.

In the Disaster Prevention Mitigation Basic Plan prepared for Istanbul, the results of the study on damages to water and sewerage networks are also included. According to these results, the damage to the pipelines is expected to be concentrated mostly in the network on the European side. The expected damages in drinking water and sewerage networks vary according to different earthquake scenarios.

As of 2019, Istanbul has 21 drinking water treatment plants, 124 water tanks and a total of 19 146 km of water network lines. In the Disaster Prevention Mitigation Basic Plan, the number of damaged points of the total 7500 km drinking water pipe network in 2003 was determined as 1395 and 1577 in various models according to the best and worst scenarios, respectively. For the sewerage network, the number of damaged points are given as 1152 and 1289.

When the maps in IMM's 2009 Possible Earthquake Losses Estimations Report are analysed, it is seen that more than half of the water reservoirs in Istanbul, especially those in the more densely populated areas, will be affected by the earthquake at various levels. In addition, drinking water distribution lines in Büyükçekmece, Beylikdüzü, Esenyurt, Bayrampaşa, Zeytinburnu and Fatih, which are denser than other districts, will also be affected.  

The area around Küçükçekmece Lake and Büyükçekmece Dam are located in the region where the largest seismic activity is expected in the earthquake. In addition, Büyükçekmece Treatment Plant (400 000 m3/day capacity), the third largest Drinking Water Treatment Plant of Istanbul, is also located in this region on the shore of Büyükçekmece Dam.  It is of great importance that this dam and the drinking water treatment plant located right next to it are not damaged in the earthquake and can continue to operate. 

Various measures are taken by ISKI for earthquake resistance in these facilities and water and sewerage distribution lines. In addition, ISKI has started the preparation of drinking water and wastewater infrastructure projects for 147 temporary shelter and assembly areas in Istanbul. 

The speed, effectiveness and prevalence of these measures are vital for mitigating the water supply risk of Istanbul after the earthquake. 

In the aftermath of the expected Marmara earthquake, a city of 16 million inhabitants like Istanbul will definitely have water problems, especially on the European side. Because Istanbul's earthquake risk mitigation efforts need a great and effective inter-institutional coordination in every field, a very strong organisation at the neighbourhood scale and the immediate renewal of the unsafe building stock of around 230 000 buildings that need to be urgently transformed. 

It is also worrying that the areas allocated for emergency evacuation and shelter have been opened for development and these areas need to be rapidly re-identified, protected and the water tanks and sewerage infrastructures placed in these areas need to be constantly monitored by non-governmental organisations.

The speed and effectiveness of the works to be carried out on these issues will prevent the water problems that will be experienced after the earthquake from reaching a crisis level.