Best Water Sources in Subnautica 2: Bleach vs Bladderfish vs Filtered Water

Why Water Management Matters

Water is often the harder survival stat to maintain in Subnautica 2. Hunger is easy to solve with fish and plants, but water requires specific processing. There are four main water sources: Bleach-derived Disinfected Water, Bladderfish Water, Large Filtered Water from the filtration machine, and plant-based water from Marblemelons and Bulbo trees. This guide compares them all.

Water Source Comparison

Bladderfish Water (Early Game)

The Bladderfish is the simplest early water source. Catch a Bladderfish and process it in the fabricator to get Filtered Water that restores +20 water. Bladderfish are common in the safe shallows and kelp forests. This is your go-to water source in the first hour, but it is inefficient because each fish only yields one small water bottle.

Bleach / Disinfected Water (Best Early-Mid Game)

Bleach is the most efficient early-game water source by far. Craft Bleach from one salt and one creepvine sample, then process the Bleach in the fabricator to get Disinfected Water (+30 water per unit). A single Bleach yields multiple water bottles, making it far more material-efficient than Bladderfish. Salt is found in salt deposits on the seabed, and creepvine is everywhere in the kelp forest. Stockpile Bleach early for a reliable water supply.

Large Filtered Water (Best Late Game)

The water filtration machine is the ultimate water source. Build it in your base, power it, and it continuously produces Large Filtered Water (+50 water) from seawater. Each bottle restores the most water of any source. The machine also produces salt as a byproduct, which you can use for curing. The downside is power cost: the filtration machine draws significant power, so pair it with a strong power source like thermal or nuclear.

Plant-Based Water (Permanent Free Supply)

Marblemelons and Bulbo trees provide water alongside hunger when eaten raw. While each individual piece restores less water than a filtration bottle, the plants are free and self-sustaining. A growbed with four Marblemelons gives you unlimited food and water without any processing or power. This is the best set-and-forget water solution for your main base.

Recommended Water Strategy

Early game: Use Bleach to make Disinfected Water. It is the most efficient use of early resources.

Mid game: Build a water filtration machine in your base once you have stable power. Switch to Large Filtered Water for maximum hydration.

Permanent: Add a Marblemelon or Bulbo tree farm for free, self-sustaining water that never runs out.

Travel: Carry Large Filtered Water bottles in your Cyclops and vehicle storage for deep expeditions.