- How to purify water: Each tool targets different contaminants — match the tool to the problem.
- UV lamp: Kills microbes only; does nothing to waste, minerals, or physical debris.
- Water filter: Removes organic waste, minerals, and physical contaminants, but not microbes.
- Pure water: Requires a Water Purifier at 100%+ quality or a Moisture Farm at 150%+ quality.
- Selling tip: Two bottles of spring water attract a Water Stockpiler buyer worth 500+ credits.
How Water Purification Works in Probably Stolen
Water purification in Probably Stolen mimics real-life contamination systems. Every water source contains a mix of contaminants, and each purification tool only removes specific types. Understanding this matching system is the difference between endless trial-and-error and a clean, automated water operation.
Video Highlights:
- Two easiest routes to high-quality water: purifier overnight, or UV lamp + water pitcher filter
- UV lamps remove microbes only; filters remove organic waste, minerals, and physical debris
- Pure water requires machine quality thresholds: 100% (purifier) or 150% (moisture farm)
- Expansion kits can be used twice to unlock extra module slots on any machine
- Spring water bottles trigger high-value Water Stockpiler buyers from day 14 onward
Here is the core contaminant-to-tool matching table:
| Contaminant Type | UV Lamp | Water Filter | Water Purifier |
|---|---|---|---|
| Microbes | Yes | No | Yes |
| Organic waste | No | Yes | Yes |
| Minerals | No | Yes | Yes |
| Physical debris | No | Yes | Yes |
Running base water through a filter alone will not upgrade its quality — the microbes survive. You must pair a filter with a UV lamp (or use a machine that handles all contaminants) to reach high-quality water.
Four Ways to Make High-Quality Water
There are four reliable routes to high-quality water, each with different setup costs and speeds. Pick based on your available machines and how hands-on you want to be.
Water Purifier (Overnight)
- Place rust water from the tap into the purifier
- Leave it overnight
- Wakes up as high-quality water
- Simplest option for early game
UV Lamp + Water Pitcher
- UV lamp kills microbes
- Pitcher filter removes waste/minerals
- Works on purchased base water from sellers
- Their mixture is ideal for this combo
Gutter Tilapia (RAS)
- Add tilapia to the recirculating aquaculture system
- Fish clean the water over time
- More fish = faster cleaning
- Check progress with the aqua scan
Hydra Weed
- Found in the old hydroponic system
- Plant seeds and let them grow repeatedly
- Each cycle cleans water slightly
- Rust water becomes base, then high-quality
A fifth option avoids purification entirely: the Moisture Farm produces base water at 55% quality, and high-quality water once you push its quality to 100.
| Method | Target Contaminants | Speed | Setup Cost |
|---|---|---|---|
| Water Purifier | All | Overnight | Medium |
| UV Lamp + Filter | Microbes + waste/minerals | Fast | Low |
| Gutter Tilapia | Specific (varies) | Slow, scales with fish | Medium |
| Hydra Weed | Specific (varies) | Very slow, multi-cycle | Low |
| Moisture Farm (100%) | Produces directly | Daily output | High |
The UV lamp + filter combo is reliable on purchased base water because sellers' mixtures are balanced. If you brew your own base water, the contaminant profile may differ and the combo may not fully purify it — scan before and after.
Step-by-Step: Making Pure Water
Pure water (99.9% purity) only comes from two machines, and both depend on machine quality modules. Follow this workflow to reach the threshold.
Stockpile Rust Water
Fill jugs with rust water from the faucet. Use a 24,000–50,000 ml water tank so you always have raw stock ready.
Pre-Purify to Base Water
Run rust water through a Hydrotek micro water purifier (or another route) to convert it into base water first.
Raise Machine Quality to Threshold
Install quality modules on your Water Purifier until it reads 100%+ quality — this unlocks its 99.9% max purity. Use up to two expansion kits to open extra module slots.
Run the Purifier Overnight
Pour the base water in and let it run overnight. A fully charged purifier consumes one charge to run a full day cycle without sleeping.
Test and Verify
Test the water after the cycle. At quality 100+, a full jug reaches pure water in roughly three nights from rust water.
Install a refinement module to push the Moisture Farm to 150%+ quality — at that threshold it produces pure water daily (around 578 ml/day at 179% quality in testing), no purification cycle needed.
| Machine | Required Quality | Output | Notes |
|---|---|---|---|
| Water Purifier | 100%+ | Pure water (99.9%) | Overnight cycle, needs charge |
| Moisture Farm | 150%+ | Pure water daily | Use refinement modules |
Machine Optimization Tips
Quality modules are the bottleneck for pure water. If you cannot hit the threshold, your machine setup needs work.
- Expansion kits can be used twice per machine, opening additional module bays beyond the default layout.
- Fill spare slots with efficiency modules to cut energy cost, or performance modules to purify more per cycle.
- Rotating machines: press E or Q to rotate, right-click to flip — essential for tight base layouts.
- Water tanks max out at 50,000 ml; upgrade storage as your high-quality output grows.
Pure-water thresholds come from big quality bonuses. Hunt for high-tier quality and refinement modules before grinding cycles — one strong module can replace several weak ones.
Selling Water for Maximum Profit
Water is one of the stronger income streams once you can produce it consistently. The key is attracting premium buyers instead of selling piecemeal.
- Place two bottles of spring water on your stall — their combined base value (over 365 total) attracts a Water Stockpiler buyer.
- From day 14 onward, stockpilers reliably appear with 500+ credits and buy all your high-quality or pure water.
- If you lack a second spring water bottle, substitute a standard of high-quality water — the combined value still triggers the stockpiler.
- Spring water sources: one bottle comes from Natalia's quest line; others can drop from random crates.
Water Operation Milestones:
- Set up overnight rust-water purification
- Install a 24,000+ ml water tank
- Reach 100% Water Purifier quality for pure water
- Collect two bottles of spring water
- Attract your first Water Stockpiler buyer
Once the stockpiler is triggered, you can replace the spring water bottles with your sellable stock — the two bottles only need to be present to attract the buyer initially.
FAQ
Q: How do I purify water to high quality in Probably Stolen?
The two easiest methods are: place tap rust water in a Water Purifier overnight, or use a UV lamp (kills microbes) followed by a water pitcher filter (removes organic waste, minerals, and physical debris). Gutter tilapia in a recirculating aquaculture system and hydra weed in the old hydroponic system also work over time.
Q: How do I make pure water?
Pure water requires machine quality thresholds: a Water Purifier at 100%+ quality purifies to 99.9% (pure), and a Moisture Farm at 150%+ quality produces pure water daily. Install quality and refinement modules, and use up to two expansion kits for extra module slots.
Q: Why won't the UV lamp upgrade my water quality?
UV lamps only remove microbes. If your water still contains organic waste, minerals, or physical contaminants, the quality will not improve. Pair the UV lamp with a filter, or use a Water Purifier which handles all contaminant types.
Q: What is the fastest way to sell water for credits?
Display two bottles of spring water (or one spring water bottle plus a high-value water) at your stall to attract a Water Stockpiler buyer. From day 14 onward, these buyers carry 500+ credits and purchase all your high-quality or pure water.