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Acid in Once Human is one of the most important resources. It’s essential for building and crafting, and it can also be converted into Portable Mixed Fuel if you have the “Super Refinery” memetic perk. There are several ways to obtain Acid in the game.
Killing Mobs
The easiest way to get Acid is to kill deviated mobs. You can find them in most locations, but the best spots allow for endless farming.
To maximize Acid collection, prepare a special dish – Preserved Deviated Chops. This food unlocks in Memetics (hotkey “O”) in the Logistics tab during the 4th week of the season, allowing you to earn 50% more Acid for killing deviants.
This effect can be further increased if the Chefosaurus Rex deviant assists you in cooking, as its bonus multiplies with the food effect, giving even more Acid from mobs.
The best spot to farm Acid by killing deviants is the Blackfell Fallen Zone. This large location allows for continuous mob respawning, making it ideal for consistent farming. This method can yield 200-300 Acid in 10 minutes.
Other locations require switching worlds using Teleportation Towers. Each world has independent mob, plant, and resource spawns, so you can clear World 1, switch to World 2, and clear it again.
Silvershore Resort is one of the most convenient spots for this. It takes less than 10 minutes to clear, yielding 150-200 Acid. However, without Preserved Deviated Chops, your results may be lower.
There’s also a location for quick Acid farming early on, near the Dayton Inspection Point Teleportation Tower (west of Coastside Plaza).
Here, you can kill low-level deviants for quick Acid. Each mob drops only 2 Acid, but it’s useful at the start since you can farm endlessly by switching worlds.
Territory Purification
An alternative to killing deviants in the open world is the Territory Purification feature. Each week, you can use up to 40 Cortexes of any level, fending off waves of monsters to gain Starchrom.
If you kill mobs manually (not using turrets or deviants), they may drop Acid, allowing for endless farming. After using 40 cortexes, Starchrom rewards stop, but you can continue using Eclipse Cortexes Lv.1, where an elite mob drops another Eclipse Cortexes Lv.1 each time, allowing indefinite purification.
This method is less profitable than open-world farming, but it’s convenient. If you place your base on water, mobs will attack only from one side, making it easy to defend.
Buying from Other Players
An easy way to get Acid in Once Human is to buy it from other players using energy links. Most resources are tradable through Vending Machines, often placed on cars around Blackfell. Switching worlds with Teleportation Towers can help you find what you need.
To track other players’ Vending Machines in the current world, enable “Vending Machine View” on the map. The fastest way to find Acid sellers is through world chat, with prices typically ranging from 60 to 80 Energy Links per unit.
Transferring Acid from Eternaland
When a Once Human season ends (usually after 6 weeks), most resources, including Acid, transfer to the Spacetime Backpack. You can bring your character to a new server along with select items. You receive 20,000 Material Points for this purpose.
This lets you get thousands of Acid in the early game, though it’s recommended to prioritize late-game tools, deviants, calibration blueprints, rare seeds, animals, Stardust Sources, etc. Watch my separate video for a detailed item transfer guide.
Sulfur Chemist
With the Sulfur Chemist memetic perk, you can produce Acid from Sulphur and Energy Links at the Synthesis Bench.
However, memetics are random, and you can only change them 3-4 times per season. If you don’t get the Sulfur Chemist perk, there’s no alternative but to accept this limitation.
Water Pumps in Contaminated Areas
In certain parts of the map, your character’s Sanity decreases, and you see the message “Stardust pollution is getting worse.” These areas, known as contaminated zones, allow Acid production if you place Water Pumps there.
Water Pumps on land (away from water) in contaminated areas extract 4 units of Polluted Water every 5 minutes. Using an Osmosis Water Purifier, Polluted Water can be turned into Impure Acid at a 2:1 ratio. Then, 10 units of Impure Acid and 1 unit of Pure Water can be converted into 1 unit of Acid in Brewing Barrels.
While this process seems complex, it generates over 1000 Acid per day passively. Watch my passive Acid farm guide and other relevant content on my YouTube channel for more details.
Contaminated Plants
You can also produce Acid from contaminated plants, which are unique to contaminated areas. Currently, the game includes Contaminated Wheat, Contaminated Berries, and Contaminated Aloe Vera.
By gathering these plants, you can collect their seeds and grow them at your base using Planter Boxes or Loamy Soils. Each contaminated plant has a growth cycle of 12 hours (though my tests show Aloe Vera may take longer), which can be halved with fertilizer.
Contaminated crops can be processed into Acid using Brewing Barrels as follows:
- 3 Berries / Wheat + 1 Pure Water = 1 Acid / 20 minutes
- 2 Aloe Vera + 1 Pure Water = 1 Acid / 20 minutes
In my separate video, I cover the Acid production math and provide breeding tips.
For automated farming, I developed a setup that requires only 2 Watts of power and produces over 400 Acid daily. Using fertilizers increases output but requires more Pure Water and power for irrigation.
For example, using 150 Planter Boxes to grow Contaminated Berries yields about 1200 fruits daily (without fertilizer). Processing these fruits gives approximately 400 Acid per day.
The farm can be automated with the Growshroom deviant, which handles planting and harvesting. All you need to do is simply add seeds to its Isolated Securement Unit twice a day. With both contaminated crop and classic Acid farms, you can produce over 2000 Acid daily.