Residents of Claket village in Mojokerto district of East Java are facing an uncertain future that could include an absolute water scarcity by 2040. That has spurred them to act and they are now looking ahead with more optimism.
They have been accumulating stocks of fresh groundwater by building absorption wells to catch rainwater to recharge freshwater supplies in the area. It could be the difference between survival and suffering in a few years' time.
Muhlis, one of the villagers, admitted that at first he was against the idea as the area is blessed with abundant freshwater springs that dot the slopes between Mount Welirang and Mount Penanggungan.
But the stark reality of gradually subsiding groundwater in the area and floods that inundated the village during the rainy season got him thinking about how to deal with water problems. In 2014 he decided to build absorption wells in the front yard of his house to catch rainwater.
"We used to bicker with neighbours and blame each other when floods occurred, but it is over now that we have the well to absorb the rainwater, which increases our groundwater supply. As you can see, the water is fresh," Muhlis told a group of journalists from Jakarta that visited his house.
The eight-cubic-metre well absorbs and stores rainwater flowing from his house and those of two neighbours. Muhlis added his own touch by installing a brick wall in a zigzag pattern on each side of the well to filter and purify the water, as well as to accelerate water absorption in the ground.
The well cost him 7.5 million rupiah (US$535) but it is expected to last for 30 years with good maintenance. It needs to be cleaned every two years to get rid of the sediment that builds up on the bottom, which is layered with palm fibres.
Other local residents have followed suit, and there are now 260 absorption wells in the village, out of the 900 absorption wells built in water catchment areas in Mojokerto.
"Building absorption wells in a water catchment area is the most effective way to conserve water," says Agus Priyono, a programme consultant with the Coca-Cola Indonesia Foundation which assisted the villagers.
The well is also an effective way to prevent seawater inundation that increasingly threatens coastal areas as climate change contributes to rising sea levels.
In addition, some residents have switched to organic farming to avoid contaminating their hard-earned fresh groundwater supply with chemicals from fertilisers.
"The produce we grow and harvest here is much better now since we turned to organic farming," Muhlis added.
The absorbed rainwater also helps to recharge supplies in nearby traditional springs and conserve them, including the 90-year-old Djoebel spring in Kembangbelor village on the slope of Mount Welirang.
Mr Priyono said the government could adopt this method in its efforts to conserve the numerous traditional springs across Indonesia. At the moment, though, there is a lack of data on the total number of traditional springs as many water catchment areas have been converted to residential and business zones amid rapid urbanisation.
A 1.5-hectare water-retention basin in Wonogiri in Central Java is one of a number of projects supported by the Coca-Cola Foundation in Indonesia. Supplied/Coca-Cola Foundation
He believes the government still lacks a strategy to preserve water catchment areas, while focusing on reforestation efforts to recreate green areas that were cleared for development purposes.
Coca-Cola, as part of its global "Water Neutral" commitment, has made water conservation one of the key goals in all the countries where it operates. In Indonesia, the Foundation has also completed two rainwater catchment reservoir projects, or embung, in the districts of Karang Anyar and Wonogiri in Central Java.
In Wonogiri, the 1.5 hectare-wide embung can hold more than 15 million litres of water and also serves as an irrigation source for at least 40 hectares of community plantations or 10 hectares of agricultural land.
The threat of a freshwater scarcity in Java, notably in Jakarta and East Java province, which could face absolute scarcity by 2040, is always cited by the Indonesian government as one of the pressing reasons why it wants to move the seat of government to East Kalimantan in 2024.
"Java remains the main industrial area. And in 2040 it is estimated that the all northern coastal areas of Java from West Java to East Java would become urban areas with the potential for a major water deficit," said Heru Santoso, a researcher from the Geotechnology Research Centre at the Indonesia Institute of Sciences.
He also said that another main cause of the depleting freshwater supply in Java is climate change. There has been a major shift in the fundamental cycle as more water into thin air dissipates due to rising temperatures triggered by climate change, and this had resulted in imbalanced water input and output.
The situation could lead to a diminished freshwater supply when at the same time the island's population continues to grow at a fast rate. About half of Indonesia's 260 million people live on Java, one of the most populous islands in the world.
"We need to raise more awareness about instilling the habit of using water wisely and moderately, and we have to keep balancing the rate of underground water," said Mr Santoso. "Some areas experience drought, but some areas have an excess supply of groundwater as well."
With more than 100 active volcanoes, many of which are located in Java, a freshwater scarcity should not be a problem for Indonesia, as springs often originate in areas where there are active volcanoes, said Asep Mulyana, a senior raw water specialist with Indonesia Urban Water, Sanitation and Hygiene Plus, part of USAID.
"The freshwater problem in Indonesia is not rooted in water scarcity but in the lack of proper water management," he said.
"Collecting water, especially during the rainy season, is therefore necessary to store it and reserve it to use during the dry season."