Finding Water

The Group A Task Force had set up a temporary camp on the deserted island. To gather more survival supplies, they split into pairs and slowly searched the island's interior.

That day, Song Zhi went out with Lai'en on a search mission. Their most important task, though, was to find water.

A few days earlier, they had found a solar panel covered in vines on the roof of the cabin. Using the principle of solar distillation to produce fresh water, Lai'en had made a solar-powered seawater desalination device. But it produced very little fresh water each day, barely enough to meet their daily drinking needs, and it tasted poor.

The two main methods of turning seawater into fresh water were thermal and membrane desalination. Both worked by separating the salt from the water.

The thermal method mimicked evaporation and rainfall in nature. Seawater was heated to produce vapor, which then cooled and condensed into droplets. It produced large quantities efficiently, but consumed too much energy to be worthwhile in the apocalypse.

The membrane method used a special semipermeable membrane to separate out the salt. It relied primarily on reverse osmosis, using high pressure to force water molecules through a reverse osmosis membrane while trapping impurities and salt. This method consumed less energy and was environmentally friendly, making it the most widely promoted.

But in the apocalypse, such technology had instead become a scarce resource.

Other methods were even more of a pipe dream. Without a functioning power grid, plasma exchange and low-temperature crystallization were both out of the question.

In the apocalypse, then, resources like electricity, heat, land, and water were what truly mattered.

Fortunately, they had found a solar panel, though they could only use the most cumbersome method to obtain water.

Speaking of condensation, Song Zhi thought of the most natural form of condensed water in nature-

"Dew!"

The two were walking side by side through a grove of towering coconut palms when Song Zhi, who had been walking with her head down in thought, suddenly spoke.

Lai'en raised an eyebrow, surprised that Song Zhi had offered an idea of her own. Though the suggestion was a little tricky, he didn't reject it outright. Instead, he raised the most crucial issue.

"Some of the plants on this island are poisonous. Drinking dew collected from them would be risky, so we'd need to tell which plants are poisonous and which aren't."

"No, I don't mean collecting dew. I mean, there's dew here and dense vegetation too, so there must be a river or an underground stream that can water the plants and help them grow," Song Zhi hurriedly explained.

She was a student specializing in the cultivation of traditional Chinese medicinal plants. To her, there was no fundamental difference between growing medicinal herbs, flowers, or grain. All plants needed six essential conditions to grow-sunlight, water, temperature, nutrients, soil, and air.

The island's vegetation was so lush that all six had to be plentiful, including fresh water for irrigation.

"I see what you mean. There aren't any visible rivers on the surface, so the water must be hidden underground," Lai'en continued, following Song Zhi's reasoning.

But underground rivers weren't easy to find, and they didn't have professional well-drilling equipment.

"Lieutenant, do you remember the shallows where we went swimming together?" Song Zhi reminded him.

Lai'en looked at her with his deep blue eyes, a hint of approval in his gaze, and gestured for her to go on.

"Ahem! The water in those shallows seeped in from the sea outside through cracks in the rocks. If seawater can seep in, then dew and rainwater can seep out. Water circulates in nature, and soil and the sun are the best purification filters." Song Zhi had nearly lost herself in those blue eyes, but fortunately, she came to her senses in time.

"Hmm, that analysis makes a lot of sense. The more luxuriant the vegetation, the more abundant the underground water resources... We can search along those lines." Lai'en nodded in agreement with Song Zhi.

He took a tactical tablet from his backpack and opened the topographic map of the island Hill had made using an unmanned survey a few days earlier. With a stylus, he circled the areas where vegetation was especially lush. According to Song Zhi's theory, underground water sources were likely hidden there, and the rise and fall of the island's mountains could also be used to analyze the course of underground rivers and where they emptied into the sea.

"We can start by investigating the nearest point. If we're lucky, we might find an underground stream," Lai'en said, pointing to a mark on the map. He shared the search area with Hill and marked it.

Song Zhi bent her head and leaned close to Lai'en, studying the map in his hands. Then she picked up her binoculars and observed the distribution of plants in the surrounding area at a distance. Some ferns and vines were growing exceptionally thickly, and those plants usually needed plenty of water to flourish like that. It showed their analysis was correct.

"That valley over there looks promising. Those plants are clearly growing much better than the ones elsewhere."

Lai'en raised his binoculars and looked in the direction Song Zhi had indicated. The environment there closely matched their analysis. After agreeing on a route, the two slowly made their way toward the target.

The road to the valley was difficult. The tall coconut grove surrounding the beach was like a natural barrier around the deserted island.

Lai'en walked quickly, cutting a path with his kukri while having to stop frequently to wait for Song Zhi. Sometimes he reached out and gave her a hand.

Although Song Zhi did her best to keep up with Lai'en, she clearly lacked his stamina and experience. She panted, fine beads of sweat forming on her forehead, but kept her teeth clenched, unwilling to fall too far behind.

The consequences of falling behind in the rainforest were still fresh in her memory. She didn't want Lai'en carrying her over his shoulder again.

Lai'en noticed her struggle and slowed his pace slightly while keeping a wary eye on their surroundings. The dense vegetation in this area blocked their view and concealed many unknown dangers.

"Can you keep going?" Lai'en's voice was low, and he seemed concerned. "If it's too much, we can take a break first."

Song Zhi shook her head and wiped the sweat from her forehead with the back of her hand. "No need, I can manage. We need to hurry. We can only ensure our safety if we find water before dark."

She was just about to straighten up and quicken her pace when Lai'en put a hand on her shoulder, stopping her.

"There's no need to rush right this moment. We can take a break and drink some water." Lai'en closed his tactical tablet and offered her a canteen, his tall, broad figure blocking the path ahead.

"All right, thank you." Song Zhi took the canteen, unscrewed the cap, and drank in small sips.

Lai'en lowered his gaze and studied Song Zhi carefully, watching every tiny change in her expression, until his stare made her uneasy. "Lieutenant..." she called timidly.

Only then did Lai'en come back to his senses. He coughed lightly to cover his lapse. "Sorry, I was just thinking... Maybe you shouldn't have come back. Was it worth it? You should be enjoying the bright sunshine in Australia right now..."

His tone was slow and measured, probing, with a hint of uncertain doubt. He wanted an answer. Although Song Zhi had given him one at the shooting range, he hadn't entirely believed her. But things were different now. Whatever she said, he would believe her completely.

Song Zhi raised her head to meet Lai'en's blue eyes and spoke slowly. "You told me to wait at the hospital. I was waiting to rejoin the team, not to evacuate with everyone else... I can enjoy freedom, special treatment, and all the care you've given me. But none of that can come at the cost of your lives... I just want all of us to survive..."

Song Zhi paused, then added, "And I don't want to become a weakness others can use to control you."