Water purification: grades, heavy metals and Pure Water

Water is graded by purity, and a litre of High-Quality Water (99%) is worth six times a litre of Rustwater. Test everything with a Water Testing Strip, then clean it in stages: tablets for microbes, a Water Filter in a pitcher for organic waste, microplastic and debris, and a Water Purifier or HydraTech Micro Water Purifier for heavy metals, which nothing else removes. Pure Water (99.9%) needs a Water Purifier with at least +100% Quality from modules: four Refinement Modules are the legal way, and they fill a standard module bay. Neural Cores also reach it but are contraband.

Grades and value

Grade	Purity	Value per litre	Notes
Pure Water	99.9% and up	80	Only a Quality-upgraded Water Purifier or Moisture Farm makes it.
High-Quality	99–99.9%	60	Upper Levels standard.
Basewater	98–99%	40	Lower Levels standard.
Ghostwater	96–98%	27	Looks clean but is unsafe; the usual mislabelling scam.
Rustwater	90–96%	10	Visible particles.
Gutterflow	Under 90%	4	Brown sewage.

A container sells for its own value plus the water: a 750 ml Standard bottle of Basewater is 5 + 30 = 35. A Jug holds 6,000 ml and a Water Tank 20,000 ml.

Which tool removes what

Tool	Removes	Limit
Water Purification Tablet	Microbes, then some chemical contaminants	One tablet cleans a large bottle of Rustwater.
Water Filter in a Water Pitcher	Organic waste, microplastic, physical contaminants, minerals	Stops working below a small amount of each; 400 durability, worn fast by Gutterflow.
Advanced Water Filter	Same as a Water Filter	Recovers 50 durability a day.
UV Lamp	All microbes	Used on a container.
HydraTech Micro Water Purifier	Brings any water to Basewater, including heavy metals	1 durability per 100 ml.
Water Purifier (machine)	Every contaminant type, a set amount each night	The only reliable way to High-Quality and Pure.

Heavy metals only leave through the Water Purifier or a HydraTech. If repeated filtering stops raising purity, the remaining contaminant is one that tool cannot remove.

Water Purifier

It costs 250 credits (cut from 300 in hotfix 1.0.0.5), uses 4 energy a night, and is sold by Dr. Jackson once you own the Water Trading upgrade. Each night it removes contaminants, largest first. Dirty water cleans much faster: up to 20× at 37.5% purity, against 1× above 98%.

Container	99% pure	90% pure	80% pure	60% pure
1 litre	35 ml	146 ml	350 ml	542 ml
3 litres	42 ml	178 ml	425 ml	659 ml
12 litres or more	69 ml	288 ml	688 ml	1,066 ml

Contaminant removed per night with no modules. Put the dirtiest water in the purifier and finish nearly clean water with tablets and filters.

Maximum purity

Since update 1.0.0.12 a purifier without modules stops at 99.01%, just inside High-Quality (it was 99.00%). Quality modules raise the cap:

Quality from modules	Maximum purity	Best grade
Under 15%	99.01%	High-Quality
50%	99.65%	High-Quality
75%	99.8%	High-Quality
100%	99.9%	Pure Water
200%	100%	Pure Water

Performance adds to the cleaning speed: +100% Performance adds +1 to the speed multiplier, which matters most on nearly clean water. Module choices are in the modules guide.

Pure Water setups

Modules in the purifier	Quality	Performance	Energy a night	Inspection risk
None	0 (cap 99.01%)	0	4	None
4 Refinement Modules	+100%	−32%	6	None
2 Capped Neural Cores	+100%	+200%	12	High-Level contraband: seized and fined
1 Uncapped Neural Core	+100%	+200%	8	Critical contraband: arrest ends the run

Four 2×2 modules are the most a standard 26-cell bay holds; a Module Bay Expansion Kit makes room for a fifth and sixth. Refinement Modules cost 100 (115 for the 5-cell shapes, which give +31% each). Dr. Jackson has one 16% of visits and always one with Jackson Investment II (650, after Investment I at 400); Engineering Foundry Supply Crates and the Underground Exchange also have them.

Nights to Pure Water with four Refinement Modules

Container	From Rustwater (95%)	From Basewater (98.5%)	From High-Quality (99%)	Value when Pure
Bottle of Water (Standard), 750 ml	1	1	1	65
Bottle of Water (Large), 2,000 ml	3	2	1	169
Jug of Water, 6,000 ml	7	3	2	495
Water Tank, 20,000 ml	17	6	4	1,950

Nights are worked out from the purifier’s removal rate, including the −32% Performance from the modules. The tooltip Contaminant Removed (Last Night) shows the real figure for your water.

A 6 L jug of Rustwater on tap does not become Pure overnight. Even with four Refinement Modules it takes about seven nights; with two Capped Neural Cores, two. Only bottles of 750 ml or less finish in one night from Rustwater. For volume, run two purifiers:

1. Purifier 1, no modules: fill a Jug from the Rustwater tap. It reaches High-Quality (99.01%) in about four nights, or a Large bottle in two.
2. Purifier 2, four Refinement Modules: finish High-Quality jugs to Pure in two nights each, 3 L of Pure Water a night.
3. Test every finished container with a Water Testing Strip and correct the label before selling.

A 6 L Jug of Pure Water is worth 495 before markup, against 375 for High-Quality. Upper Levels stockpilers, who buy both, have 500–600 to spend and test what they buy. The HydraTech Micro Water Purifier skips step 1 by bringing any water up to Basewater at once, but it wears 1 durability per 100 ml, so a jug costs 60.

Moisture Farm

It makes 850 ml of Ghostwater a night into any container with room (350 credits since hotfix 1.0.0.2; 6 energy a night). Update 1.0.0.12 fixed a bug that capped output at 6 L. Each +50% Quality raises the output one grade; any negative Quality drops it to Rustwater.

Quality from modules	Water produced
Below 0%	Rustwater or Gutterflow
0 to +49%	Ghostwater
+50 to +99%	Basewater
+100 to +149%	High-Quality
+150% or more	Pure Water

Without contraband, Pure Water from a farm means six Refinement Modules (+150%, −48% Performance, about 440 ml a night), which needs one Module Bay Expansion Kit. Four make High-Quality Water at about 580 ml a night.

Farms share the station’s air. Two farms make 680 ml each (1,360 total), three 570 each (1,710), four 484 each (1,936). Past three or four farms, a Performance module (+136 ml per farm) beats another farm.

Buying and selling

• Water sellers come when a Water Neon Sign is in the Display Case. Some of their Basewater is Ghostwater. A testing strip costs 3 credits.
• If water tests worse than its label, confront the seller and the price drops to match.
• Wild’s Network taps: Gutterflow On Tap (250) and Rustwater On Tap (350) give unlimited dirty water with a purity that changes daily. The Working Pipes perk starts you with Rustwater.
• Buyers go by the label: Scavengers want Basewater or Ghostwater (60–100 credits budget), Lower Levels shoppers Basewater or High-Quality (145–195), and Upper Levels stockpilers High-Quality or Pure (500–600) and carry testing strips.
• Take the filter out of a Water Pitcher before selling it.

Relabelling

The Labeler can mark Ghostwater as Basewater (it also unlocks Lower Levels Special). A buyer who tests the water catches you. Every sale of mislabelled or dangerous water is tallied, and past 2,500 ml it becomes Fraudulent Misrepresentation or Consumer Endangerment on your Security Record, plus 20 per further 500 ml. Sales to tourists do not count. See inspections and investigations.

Water for crops and wine

Hydroponic plants lose health to heavy metals, chemical contaminants, microbes, organic waste, acid and base above 0.10% each; see the hydroponics guide. Wine needs Basewater or High-Quality Water: the fermenting guide says Pure Water lacks the minerals fermentation needs. See winemaking.