Lu Yan sat on the ground and looked at the crooked drainage channel in front of him. Although it already has the function of drainage, it has no stone reinforcement. Although the soil drainage channel looks very solid now, as long as it experiences a few heavy rains, the soil will become softer and will soon collapse and be blocked!

However, Lu Yan swept the goods in the trading shop and found no powder concrete for sale at all. Even the clay and glue that made concrete could not be found.

"It seems that I have to use the [upgrade] function of the system."

Lu Yan called out the system interface and looked at the drainage channel. Soon, two prompts appeared in front of him.

【A drainage trench (upgradable)】

[Upgrade method 1: Use stone material to reinforce, improve the firmness, resist corrosion, and be easy to clean! But it is easy to be damaged and requires 80 survival points!]

[Upgrade method 2: Use plastic and stone pipelines to bury underground pipes to increase concealment, not easily be damaged, reduce bacterial growth, and avoid foul odor spread, but it is difficult to clean after blockage! 200 survival points are required!]

The upgrade method of drainage canals is surprisingly similar to the placement of safe houses, both of which have two options: above and below ground.

"From the perspective of the two options, underground drainage canals must have more advantages, but I have too few survival points now, so I have to spend all my money on the blade..." Lu Yan thought for a while, but decided to choose the first upgrade method. When there are too many survival points in the future, the worst thing is to transform the drainage canal.

Only 10kg of stone was left in his backpack. After taking it out and putting it in the drainage channel, he found that the survival point needed for upgrading was reduced to 75 points.

Lu Yan touched his chin, and he strided around the back of the safety room, picked up some stones and put them together with the previous stone.

After picking up about a few kilograms, the demand for survival points slowly became 74.

"Sure enough, the amount of stone required to upgrade the drainage canal is limited to the quantity, not the material... As long as it is stone, there is no difference between pebbles and ores!" Lu Yan discovered an important information, which made him very excited: "Does this mean that as long as enough stone is collected, my safe house can also be upgraded to stone in a short period of time?"

An hour later, Lu Yan picked up all the stones within a 1,000-meter range of the safe house.

However, due to terrain, the location of the Luyan Security House is far away from the mountains, so even after collecting all the surrounding stones, it is only about a dozen kilograms.

[Upgrade method 1: Requires survival point 70!]

"This is not a solution. There are too few stones nearby. Just buy goods in the trading yard!" Lu Yan looked at his palm, which had been ground into blood, and then looked at the sun that had risen above his head. It was about to reach the hottest time of the day. He had to complete the drainage work before that and return to the safe house, otherwise he would be at risk of heatstroke.

Scan the goods directly at the auction house is the most convenient way.

After all, Lu Yan now has a common currency such as "drinking water", and he can exchange anything he wants.

Don’t say that Lu Yan’s uncontrollably use drinking water to buy various goods is a stupid act. He said that he could leave the water and spend more time and energy to go to a farther place to collect stones...

In the doomsday, time is also an important resource.

If Lu Yan wants to pick up enough stones for the expansion of the drainage channel, it may take one or two days, and to go further away, not to mention the waste of time, he will also need to consume a lot of water and food in these or two days, which will consume more than direct transactions and purchases!

His efforts and gains will be completely disproportionate!

What's more, in the early days of the doomsday, the price of resources such as stone, which are everywhere, is very low, and you can buy a lot of them with just a little water.

【Seller: Lu Yan】

[Sold items: 10 ml of drinking water (1000 ml in total)]

[Required items: 40kg stone]

[Note: Buy a large amount of stone, each person can only exchange it three times!]

After drinking water was put on the shelves, the transaction information quickly rang out.

[Player Su Chen bids 120kg of stone and gets 30 ml of drinking water!]

【Player…】

Lu Yan’s behavior of using drinking water to exchange stone is no less than a savior for some players struggling with the hunger line. You should know that in the early stage of the doomsday, most players regard stones, such as "resources" that can be seen everywhere as garbage. So far, there is no precedent for successfully selling stones in the trading field!

And at this time, Lu Yan's move naturally made many people deeply confused.

[Duan Xiu: What he bought is so strange, stone... what can be used for now?]

[Hong Wen: Lu Shen! My safe house is near the mine. How much stone do you need? I contracted it myself!]

[Li Qiunan: Everyone, do you think there is such a possibility... The God of Lu uses this method to help some people who cannot drink water? After all, stones are now equivalent to garbage. Who would be willing to buy garbage with the most precious water source?]

[Lu Shan: Surely! Lu Shenren is still very kind. He wants to help others, but he doesn't want them to have the idea of ​​getting something for nothing... So he uses this kind of stone that anyone can get to change water, so that we know that if we want to drink water, we have to rely on our own efforts to fight for it!]

【xx: The God of Road is grand, and the love is boundless!】

【xx: Listen to me, thank you because of you...】

In the World Channel, a considerable number of players actually recognized this reasoning because they really couldn't imagine what Lu Yan's use to acquire a large amount of stone. Under the leadership of several rhythm masters, the World Channel is full of brainless praise for Lu Yan...

As the saying goes, self-guidance is the most terrifying. Lu Yan did not expect that his simple trading behavior would make so many people regard him as a good person, but he was too lazy to explain. After all, "reputation" is also an important resource. Although the performance was not obvious enough in the early stage, the more order was established in the wilderness and survival was stable, the importance of "reputation" would gradually be revealed.

【You lost 1000 ml of drinking water】

【You get 4000kg of stone】

After two prompts, a large amount of stone appeared in front of Lu Yan. He tried to put the stone into the drainage channel, watching the survival point of the need for little rewards. Finally, after 540kg was placed, the survival point was frozen at 20 and no longer moved. No matter how much stone was added, the survival point would not change anymore.

"Have you reached the limit?" Lu Yan touched his chin. It was obvious that the stone required for the drainage channel reached the upper limit. If you want to continue to reduce the survival points, you need to add some concrete. Even after adding concrete, the survival point cannot be reduced to 0, because the system will also require a "labor fee" to help complete the upgrade.

Previously, the safety house added load-bearing columns, and 5 survival points were consumed when the materials were complete. The "labor fee" for upgrading the drainage channel should be similar to it when the materials were complete.

"Confirm to upgrade!" Lu Yan chose the upgrade method 1 neatly. With a pleasant prompt sound, green light shrouded the drainage channel.

The light dissipated, and all the stone had turned into stone slabs, neatly laid in the drainage channel, and the gaps were tightly bonded by cement!

A stone drainage channel extends directly from the door of the safety house to a depression fifty meters away!

【A complete drainage channel】

【Drainage performance: Excellent】

【Anti-permeability: Excellent】

【Function: In the case of heavy rainfall, it can ensure that there will be no accumulation of water near the safe house and prevent backflow from occurring!】
Chapter completed!