A STUDY ON THE PROJECTION OF DRINKING WATER 2023-2033 IN DKI JAKARTA INDONESIA

Purpose: The purpose of this research is to analyze the drinking water needs and raw water availability of DKI Jakarta Province. Theoretical framework: The theoretical basis for the population projections uses mathematical modeling (arithmetic, logarithmic, exponential, and geometric) for the next 10 years. Drinking water demand projections are obtained by calculating the demand for drinking water and the results of the population projections. Then compared to raw water availability. Potable water demands are calculated based on design criteria Method/design/approach: The method used is research and development by projecting the population of the last 10 years to predict the population of the next 10 years. The total projected drinking water needs obtained were compared with the availability of raw water. Results and conclusion: The results show that the demand for drinking water in DKI Jakarta in 2023 will be 30,892 liters/second, while the raw water capacity will only be 16,850. This shows that the level of drinking water service in DKI Jakarta is only 54.54%. When compared to 2015, DKI Jakarta's drinking water access service decreased from 65.13% in 2015 to 54.54% in 2023. Research implications: If DKI Jakarta does not succeed in finding raw water sources, it is estimated that drinking water services will drop dramatically to 35.68% in 2033. Originality/value: Studies on the projection of drinking water in DKI Jakarta, Indonesia for the next 10 years have not been conducted. So this study has good originality and becomes a study with high novelty. This study can also be utilized by DKI Jakarta government authorities in formulating environmental and health management policies.


INTRODUCTION
Water is abundant in nature, with many sources that humans can utilize to meet their daily water needs. Water is a mandatory component in human survival. Every day humans use water for many things to fulfill their needs. Humans make use of water sources from existing nature, to then process it into water that is suitable for their use (Jamwal, 2019). Raw water for drinking water is an important factor in the continuation of human life and other living matters (Karimi Alavijeh et al., 2021). Raw water for human drinking water must meet several characteristics, including physical, chemical, and biological characteristics (Chhabra, 2017;Luby et al., 2018;Muharemi et al., 2019).
Contaminated drinking water can lead to various waterborne diseases (Cifuentes et al., 2002;Nafi'u & T K, 2016;Njiru et al., 2016;Nyagwencha et al., 2013). Study review conducted by Firmansyah et al. (2021) drinking water quality contaminated with E. coli can cause diarrhea in toddlers (Firmansyah et al., 2021). Diarrhea disease globally is one of the waterborne diseases with a mortality of 1.8 million people with the number of cases per year reaching 4 billion (WHO, 2014). Study in underdeveloped countries, diarrhea in children causes up to 90% mortality (WHO\UNICEF, 2021). WHO revealed that 6.3% of deaths in the world are caused by access to unsafe drinking water, hygiene, sanitation facilities, and poor water management (Prüss-Üstün et al., 2008). In line with WHO, the United Nation announced that 780 million people of the world's total population lack access to safe clean water, and 2.5 billion people in developing countries live with inadequate sanitation facilities (WHO, 2014).
Water usage can be grouped into several purposes such as household needs which are usually used for drinking, cooking, bathing, washing purposes, and others (Haghiabi et al., 2018). Meanwhile, for industrial purposes, water is used as a staple in the beverage or food industry, besides that water is also used as an auxiliary material, such as cooling water, washing water, and others (Raux-Defossez et al., 2018). Water is also used for public purposes such as for the maintenance of city parks, drainage of city channels, water supply for fire fighting, and many more (Kondo et al., 2019).
The availability of drinking water that meets the requirements for human needs is relatively small because it is limited by various factors (EL-Nwsany et al., 2019). Such exploitation of natural resources can lead to reduced groundwater reserves in the future (Susilo & Jafri, 2019). The magnitude of human needs for water leads us to be able to design drinking water supply systems, to provide drinking water that continues to meet human needs. Many sources of water can be utilized, such as springs, rivers, and even seawater and wastewater have been further treated to be consumed as drinking water. Water from various sources is further treated before being distributed to consumers.
Communities in the current era are no longer the object of development, but rather the subject of development (Goel et al., 2020). Therefore, for drinking water and sanitation issues, it must be carefully carried out as well as possible by the relevant parties. This can be done with the Acceleration of Sanitation and Settlement Development. District sanitation working groups, which are the pioneers in implementing the Acceleration of Sanitation and Settlement Development in the regions, need to instill sanitation ideology in stakeholders, the private sector, and the community to achieve universal access to the sanitation and water supply sectors (Muller et al., 2017). The lack of regional readiness to achieve this is a challenge in this universal access program. therefore,.
Drinking water with good quality and quantity is related to environmental conditions. The damaged environment can be caused by the increasing population. The increasing population increases the need for drinking water. Therefore, good handling is needed in processing, supplying and distributing drinking water, to meet the needs of the community for drinking water. So it is necessary to collect data on the drinking water needs of an area and the availability of raw water for a drinking water supply system design. So that a drinking water supply system is formed that is able to meet the needs of the community continuously and has a good level of service. The purpose of this research is to analyze the drinking water needs and raw water availability of DKI Jakarta Province.

THEORETICAL FRAMEWORK
The secondary data collected was the population for the last 10 years of DKI Jakarta Province. This data is used to project the population to determine the need for drinking water in the next few years. The population of the last 10 years of DKI Jakarta province can be seen in table 1, In addition to 10-year population data, the data needed is the availability of raw water in DKI Jakarta Province. The availability of raw water processed by two PAM Jaya operators, Palyja and Aaetra, can be seen in Table 2, The population for the next few years will be projected using several methods. The methods to be used are arithmetic, logarithmic, exponential, and geometric. The methods will be compared and the best method will be selected to be used in projecting the population of DKI Jakarta for the next 10 years. Projections of drinking water demand are obtained by calculating the demand for drinking water and the results of population projections. Then compared with the availability of raw water. Drinking water needs are calculated based on design criteria. Drinking water supply design criteria can be seen in table 3, The study was also used in water scarcity, water demand, water resources, water pollution until 2050 in several countries such as Pakistan, India, Bangladesh, Angola, Malawi, and Uganda (Boretti & Rosa, 2019). In line with this method, in Myanmar, it is used to determine the needs of irrigation water use, domestic activities, and drinking water (Re et al., 2021). Study in the City of Dili East Timor-Leste using geometry model projections for water ___________________________________________________________________________ Rev. Gest. Soc. Ambient. | Miami | v.17.n.1 | p.1-12 | e03157 | 2023. 5 utilities in the 2017-2027 timeframe (Santos & Santosa, 2020). Geometric modeling is also used in Germany for drinking water reservoirs and potential adaptation strategies (Mi et al., 2020). This study will be helpful in supporting effective water supply and the achievement of sustainable development goals (Grejo & Lunkes, 2022). In addition, it can be used as an environmental instrument to inform policy formulation (Silva et al., 2022).

METHOD
This study used a research and development method. The research conducted in this study is the availability of raw water in the DKI Jakarta province of Indonesia in 2023. The first development conducted in this study is population projection and population comparison using arithmetic, logarithmic, exponential, and geometric modeling in 2011-2033. The second is the projection of drinking water needs in DKI Jakarta province, Indonesia in 2023-2033. Third is the existing drinking water services in DKI Jakarta province. This study uses secondary data, with data sources from the journal for the total population in DKI Jakarta province during 2011-2020; data sources for the availability of raw water sources are obtained from the Jaya DKI Jakarta drinking water treatment agency.

The Projection of Total Population
The projection of the future population serves to estimate the need for drinking water. The population of DKI Jakarta will be projected for the next 10 years using four projection methods, namely,arithmetic method, logarithmic method, exponential method, geometry method. Determination of the best method is obtained by comparing the four methods, namely by looking at the standard deviation value (S) which is the smallest and the correlation coefficient (R) which is close to 1 for each method. Population growth projections with the 4 methods can be seen in Table 4. From the four population projection methods a comparison of population growth can be obtained as shown in table 5 and figure 1 ,  Based on the S and R values, it can be seen that the arithmetic method has the smallest S value, namely 0 and the R value is 1. Then the population projection method chosen is the arithmetic method. The projected results of the selected population can be seen in table 6,

Projection of Drinking Water Needs
The projected need for clean water is calculated based on the projected population which will be served until the end of the planning year and water demand standards drink for all kinds of customers. Basic calculation for a capacity system, the stages are determination of service areas, population projections, total population served, comparison of SR and HU, determination of water consumption and water loss, loss of water, factor maximum days and peak hours. The final capacity of clean water products besides being determined by the amount to be served, on the other hand is limited by the availability of raw water and financial feasibility from the results of a socio-economic survey. From the results of this study it can be seen that the ability and willingness to become a customer will ultimately determine the service ratio between house connections and public faucets.
Determination of the ratio between the house connection and the public faucet determines the amount of water capacity needed for domestic use directly and the total need for clean water indirectly. Calculation of domestic needs increases in line with the increase in population (Jaiswal et al., 2018). The steps for calculating the need for clean water, firstly calculating the required water discharge according to the potential of the customer exist in the service area until the end of the planning year. Secondly, allocating water discharge according to the results of the calculation after taking into account the crest factor and water leakage (Luo et al., 2018(Luo et al., , 2019Myronidis et al., 2018). There are several standards for drinking water issued by national and international institutions. One of the drinking water demand standards issued by the Ministry of Settlement and Regional Infrastructure in 2003 can be seen in Table 3. The projected demand for drinking water for DKI Jakarta can be seen in table 7.

Analysis of Raw Water Availability
DKI Jakarta in the provision of drinking water is the responsibility of water company Jaya. Water company Jaya has two operators that share the service area. The operators are Palyja and Aetra. Palyja serves West Jakarta, South Jakarta and parts of Central Jakarta, while Aetra serves East Jakarta, North Jakarta and parts of Central Jakarta. The division of service areas can be seen in Figure 2. In 2015 the raw water capacity processed by the two operators was around 17,000 liters/second, while the demand for drinking water at that time was 26,100 liters/second. This means that DKI Jakarta is short of drinking water of around 9,100 liters/second. Or only fulfilled by 65.13% serving 5,804,500 people out of the total population of DKI Jakarta 10,177,924 people (DPMPTSP DKI Jakarta, accessed 2023). The availability of raw water in 2022 by the two operators is still at 16,850 liters/second. It consists of 6,850 liters/second from Palyja (Palyja, 2022) and 10,000 liters/second from Aetra (Aetra, 2022). Meanwhile, the need for drinking water in 2023 is 30,892 liters/second. The deficit that was met was 14,042 liters/second. In 2023 the population of DKI Jakarta served by access to drinking water is estimated to be around 54.54% of the total population. This figure has decreased by around 10.59% from 2015 with drinking water services of 65.13%. If water company Jaya does not look for new raw water sources, it is estimated that in 2023-2033 DKI Jakarta's drinking water services will drop drastically. For more details can be seen in table 8, Sources of raw water to fulfill drinking water in DKI Jakarta come from within the province and outside Jakarta (Ardhianie et al., 2022;Gumelar et al., 2020;Nahib et al., 2022). Water sources originating from DKI Jakarta are the Krukut river 4% and Cengkraeng Drain 1.7%. Meanwhile, other fulfillment comes from outside Jakarta which comes from Jatiluhur Reservoir 62.5%, water treatment plant Serpong 31%, and water treatment plant Cikokol 0.8% (DPMPTSP DKI Jakarta, accessed 2023). Actually there are 13 rivers in DKI Jakarta that have not been properly utilized as raw water sources. This is because the river is polluted. So it requires processing technology that is better than what already exists in Indonesia. Related to this, several countries have made efforts to treat domestic wastewater for reuse as drinking water.

FINAL CONSIDERATIONS
The projected results for DKI Jakarta's drinking water needs in 2028 and 2023 are 38,772 liters/second and 47,220 liters/second. The availability of raw water in 2023 is only 16,850 liters/second. That means if DKI Jakarta does not look for alternative raw water sources, DKI Jakarta's drinking water services will drop drastically from 65.13% and 54.54 in 2015 and 2023 to 43.46% and 35.68% in 2028 and 2033 respectively. will come. For this reason, it is necessary to develop drinking water treatment technologies that can process river water, which is already the fastest in DKI Jakarta. So that drinking water services for DKI Jakarta can be fulfilled.