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ONCE HUMAN: Acid Production Using Water Pumps (Breakdown)

Every player in Once Human can produce Acid. This is crucial because Acid is necessary for smelting high-grade metal ingots (e.g., aluminum and tungsten), which are essential for crafting and upgrading equipment.

Where You Can Produce Acid

To produce Acid, you need to extract Polluted Water using Water Pumps. This is only possible in so-called Contaminated (or Polluted) Areas. In such zones, your character’s backpack starts blinking, and their sanity decreases, which reduces maximum HP.

Once Human

To locate contaminated zones easily, use an interactive map via the link

  1. Select the scenario you are currently playing. This is important, as the “Way of Winter” scenario has a different world map.
    interactive map
  2. Open the “Filter” panel and go to the “Search” tab.
    interactive map
  3. Type “contaminated area” into the search field and press Enter. This way you will get a list of all contaminated areas on the selected map.

Important About Placing Water Pumps

If you place a Water Pump too close to any body of water (river, lake, sea, etc.) within a contaminated area, it will extract:

  • 4 Polluted Water during the first interval (5 minutes),
  • 24 Dirty / Sea Water during the second interval (the next 5 minutes).

Once Human

This approach is not efficient for Acid production. Make sure your Water Pumps are placed on solid ground far enough from any bodies of water.

Acid Production Process & Math

To produce Acid, you must extract Polluted Water with Water Pumps and process it into Impure Acid using an Osmosis Water Purifier. Afterward, combine Impure Acid with Pure Water in a Brewing Barrel to get Acid. For maximum efficiency, follow these ratios: 10 Water Pumps and 2 Brewing Barrels per 1 Osmosis Water Purifier.

Here’s a detailed breakdown:

  • Each Osmosis Water Purifier has 4 input slots, processing 2 units of Polluted Water into 1 unit of Impure Acid per minute.
    Once Human
  • To fully utilize its capacity, you need (2 units × 60 minutes × 4 slots) 480 Polluted Water per hour, resulting in 480 ÷ 2 = 240 units of Impure Acid.
  • A single Water Pump extracts 4 units of Polluted Water every 5 minutes or (4 units × 60 ÷ 5) 48 units per hour. This means you need 480 ÷ 48 = 10 Water Pumps per Osmosis Water Purifier.
    Once Human
  • To produce 1 unit of Acid in a Brewing Barrel, you need 10 units of Impure Acid, 1 unit of Pure Water, and 20 minutes of real time.
  • Each Brewing Barrel has 4 slots, allowing it to process (10 units × 4 slots × 60 ÷ 20) 120 units of Impure Acid per hour.
    Once Human
  • Since 1 Osmosis Water Purifier produces 240 units of Impure Acid per hour, you need 240 ÷ 120 = 2 Brewing Barrels.
  • Thus, the setup produces (240 Impure Acid / 10) 24 units of Acid per hour.

This setup consumes 130 Watts of power. If you generate enough electricity using Electric Eels or Memetic Specializations, you can scale up to 3 such setups in your base, yielding 72 units of Acid per hour.

How To Unlock the Required Facilities

Press “O” to open the Memetics and go to the “Logistics” tab. Starting from the week 2, you can unlock the branch that includes Rainwater Collection System, Water Tank, filters and pumps.

Once Human

How To Produce Pure Water and Polluted Water Simultaneously

There is a simple trick that allows you to do this. The key is to place your territory on the border of a contaminated area so that one half is within the polluted zone, and the other half is outside. In the contaminated part, you can place your Acid farm and Deviation Energy Generators, and in the normal part, your Pure Water farm.

Once Human

It’s not difficult to find the border of a contaminated area. Just locate a place where your backpack starts blinking and move your territory there, so that its center is exactly on that spot.

A Simple Acid Farm (Building Guide)

Not so long ago I posted a video tutorial on building an Acid farm on my YouTube channel.

YouTube video cover
Automatic Acid Farm v3.0 (after the update) | ONCE HUMAN

Specifics of Offline Acid Production

At the moment, you can’t produce Acid effectively while offline. The thing is that your facilities (Water Pumps, Osmosis Water Purifiers, etc.) will not work correctly if they are not loaded into the world, which can cause issues. Therefore, after building an Acid farm, I recommend enabling it only while you are playing.

Technically, if your territory is near a spot popular among players, it will be periodically loaded into the world when they get close. This might yield slightly better results, but I wouldn’t rely on this.

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