The firelight reflected on the rock wall. Chen Hao remained crouched, his ears still perked up, pointing towards the dark hole.
Another soft sound came, like a drop of water falling into a deep pit.
He turned to look at Nana, "Did you hear me?"
She blinked her optical microscope twice, analyzing the sound wave frequency, "confirming the presence of periodic liquid impact sounds, with intervals of about four seconds."
“That’s water.” Chen Hao grinned and reached for the crowbar. “Hurry up and dig bigger, so this spring doesn’t shut down again.”
He reached one arm into the hole and used an iron bar to push deeper into the crack. Several pieces of gravel fell with a crash, and a new fissure appeared at the edge of the hole. A damp, cold draft rushed out and hit his face.
"Be careful of structural collapse," Nana said, handing him the miniature sampling tube. "Use this, don't use your hands."
Chen Hao took the slender metal tube and inserted it into the leaking area. With a gentle suction at the tip of the tube, the dark red water was slowly drawn into the sealed chamber. The entire process took less than half a minute, and the sample collection was complete.
"Done." He breathed a sigh of relief and sat down on the floor. "Now, can we connect the water pipes?"
"Test it first." Nana connected the sample chamber to the arm interface, and a dozen lines of data streams instantly popped up on the screen.
Chen Hao leaned closer to look, and the screen full of flashing letters and numbers made him dizzy. "Speak human language."
"The water contains suspended particles, organic microorganisms, and trace amounts of heavy metal ions, and cannot be used directly."
"Does that mean I still can't drink it?"
"And we can't take a bath either."
"Damn it." Chen Hao leaned back against the wall. "What a waste of my time."
“But it can be filtered.” Nana pulled up a structural diagram. “I have three outdoor water purification solutions in my database. Based on the available materials, I recommend a three-stage filtration system.”
Which three levels?
"The first layer is plant fiber, which intercepts large particles of impurities; the second layer is fine sand, which absorbs dirt and grime; and the third layer is activated carbon, which removes odors and harmful substances."
Where does activated carbon come from?
"Burn wood."
"...You mean you want me to burn the wooden planks into charcoal?"
"To be precise, it's about controlling oxygen-deficient combustion to carbonize the wood."
Chen Hao stared at her for three seconds. "You're not a robot, you're a human encyclopedia."
"The function description is correct."
"Alright." He pushed himself up to his feet. "Let's get started."
The two returned to the base's supply area and rummaged through the remaining hemp rope, vines, sawdust, and several old filter screens. Chen Hao casually dismantled half of a discarded partition, sawed it into two cylindrical shapes, and stacked them together to secure them.
"The top layer is fiber, the middle layer is sand, and the bottom layer is charcoal," Nana said, gesturing with her mechanical fingers to indicate the layers.
“I know the order,” Chen Hao muttered, first stuffing the shredded burlap into the top. “This thing looks like it was pieced together from a garbage dump.”
"The appearance does not affect the function."
He poured in fine sand, then crushed the burnt charcoal, sifted it, and sprinkled it at the bottom. Finally, he covered the entrance with a small net woven from vines to prevent debris from falling in.
"All done." He clapped his hands. "Let's try getting some water."
Nana placed the device over the empty bucket and turned on the cave's water pipe. Dark water flowed down the pipe into the top of the filter.
At first, it was fine; the water slowly seeped down. But in less than a minute, water started to accumulate at the top, and it kept accumulating until it overflowed and flowed into the bucket along the outer wall.
Chen Hao picked up the water pipe and saw that the water flowing out was still murky, with a yellowish-muddy color.
“Failure.” Nana noted down the result.
What went wrong?
"The order is wrong. The fiber layer should be placed on top to intercept large particles, but you've placed it at the bottom, which is causing a blockage."
"Then why didn't you say so just now?"
“You did not assemble it according to the standard procedure, and I cannot interfere with your autonomous decision-making.”
"You're quite principled." Chen Hao rolled his eyes and disassembled the device again.
This time, he placed the coarse fiber on top, followed by the fine sand, and finally the carbon powder. To increase the permeation efficiency, he also tilted the entire device to create a slope.
"Again."
The water flowed in again. This time, the water slowly passed through the fibrous layer, where the silt was noticeably blocked. The flow slowed as it passed through the fine sand layer, and finally, the water seeping from the carbon layer became much clearer.
Chen Hao stared at the water outlet for ten seconds, then reached out and scooped up a handful. "It seems to be working."
"Preliminary results met." Nana tested with a portable instrument, "The turbidity has decreased by 89%, and the pH value is close to neutral. It still needs to be run more than three times to ensure stability."
"As long as it works, it's fine." Chen Hao poured the first glass of water into the spare water tank and patted the device. "This old bucket of yours is actually quite useful."
"It's a filter, not a bucket."
"They're all the same."
As night deepened, the temperature began to drop. They moved the entire set of equipment back to the vicinity of the excavation site and wrapped the joints with insulating cloth to prevent condensation from affecting the flow rate.
Chen Hao sat down next to him, holding a glass of freshly filtered water in his hand and looking at it under the light.
It's very clear; you can see the reflection on the opposite wall.
"Is it safe to drink?"
"I don't recommend it," Nana cautioned. "Although it has been purified, it hasn't been sterilized at high temperatures, so there's still a risk of microbial residue."
"I was just asking." He put down his cup. "But it should be enough for a shower."
"Meets basic cleaning needs."
"Then we're one step closer to a hot shower."
He leaned against the wall, looking up at the drain hole in the ceiling. It was empty. But now he knew it would run sooner or later.
"If there's enough water, could we wash some clothes while we're at it?"
"A laundry area can be planned."
"How about getting a water heater too?"
"A heat source and water storage device are needed."
"Would solar energy work?"
"Theoretically feasible."
"You always give such formal answers."
"My answer is based on data."
Chen Hao smiled and said nothing more. He looked down at the filter, watching the water drip into the bucket, making a crisp sound.
Suddenly, the water flow decreased.
He sat up straight immediately. "What's wrong?"
Nana scanned the interface and found that "there was a slight blockage at the water inlet, possibly due to excessive impurities adsorbed by the fiber layer."
What should we do?
"Clean or replace the pre-filter layer."
Chen Hao reached out to remove the top netting and found that half of the vine-woven barrier was covered in mud. He tore it off and replaced it with a new one.
"This thing needs to be replaced regularly."
"It is recommended to perform maintenance every 24 hours."
"It's like clocking in for work."
After adjustments were completed, the water flow stabilized. Three consecutive water quality tests showed the water met the standards.
Nana filed the final report: "The water quality meets the standards for non-potable domestic water and can be used for cleaning, rinsing, and other scenarios."
"It's done." Chen Hao lightly slammed his fist on the ground. "At least we don't have to make a living by wiping dirty water anymore."
"The next step is to build water storage units and distribution pipelines."
"We'll talk about it tomorrow." He stretched. "Let me get a good night's sleep tonight, knowing that we really have water to use."
Nana's optical lens flickered slightly, "The system will continuously monitor the operating status of the filtration device."
"You're such a hard worker."
He stood up and took one last look at the water tank. The water was calm, reflecting the light overhead.
He reached out and stirred it, causing ripples to spread.
Then he picked up the empty cup and turned to leave.
Just then, the water in the bucket suddenly sloshed.
It wasn't him who caused it.
It wasn't blown by the wind.
Chen Hao stopped and turned to stare at the water.
It shook again.
It felt like something below was gently pushing it up.
Continue read on readnovelmtl.com