Onsen Springs

Discover natural hot springs, explore their mineral properties, and build your own Japanese-style bathhouse.

Onsen Springs adds natural spring veins, a compass for finding them, water collection and analysis, mineral-water mixing, bathing effects, onsen eggs, and bathhouse decorations.

Requirements and installation

• Minecraft Java Edition 26.3

• Java 25

• Fabric Loader 0.19.5 or later

• Fabric API 0.161.0+26.3 or a compatible later version

Place the mod JAR and Fabric API in your mods folder. For multiplayer, install both on the client and server.

When updating, remove the previous Onsen Springs JAR. Do not install multiple versions together.

Several item names, messages, and analysis reports are currently displayed in Japanese, including when the game language is English.

Finding and preserving springs

Hold an Onsen Compass in your main hand or offhand to search for natural springs. The needle shows direction only, without distance or depth. A spinning needle means a search is in progress.

Right-click to search for a different spring, excluding the previous spring cluster. If another spring cannot be found, the compass returns to its previous target. Move to another area and try again. Putting the compass away pauses an ongoing search.

Preserve Spring Vein blocks. Breaking one removes that block's ability to produce water. It drops no item, even with Silk Touch, and cannot be collected and relocated in survival. Collect the water instead.

Collecting and analyzing water

Use a Hot Spring Bucket to collect water directly from a Spring Vein or a full hot spring water source block.

• Collecting directly from a vein preserves the vein.

• Collecting from a water source removes that water block.

• Flowing water cannot be scooped.

• The decorative Bath Bucket cannot collect water.

To analyze water, carry paper and right-click an Analysis Table with a filled Hot Spring Bucket. Each report consumes one sheet of paper, while the water remains in the bucket.

Hold the report or display it in an item frame. It shows spring type, temperature, pH, mixture percentages, available effects, and source yield where applicable. Displayed pH is a simplified game value.

Mixing and cooling

Pour water into an empty or flowing space connected to your bath. Connected water mixes throughout the bath. Keep separate pools physically separated to preserve different waters.

Temperature and mixture ratios depend on the amounts mixed. Ordinary water is treated as 10°C: adding it cools the bath and dilutes its benefits.

Mixing rules count different spring types, not individual sources:

• One type: normal effect duration.

• Two types: a type making up more than half of the mineral mixture retains its normal duration; the other has half duration. Equal portions give both half duration.

• Three types: each effect has one-fifth of its normal duration.

• Four or more types: treated as ordinary water for bathing benefits, with no spring effects.

Ordinary-water dilution further reduces effect duration and cleansing chance. It does not remove spring types already present or restore benefits lost from mixing too many types. Analyze the bath again after mixing.

Connected regions larger than 4,096 water cells cannot be mixed. Avoid connecting a bath to a large lake or ocean.

Bathing

Hot spring water must reach your waist. Stay in the water for the required time, then leave it to receive the effects.

Water below 38°C provides no bathing benefits. Water at 46°C or above provides no bathing benefits and causes damage during sustained waist-level contact.

Long baths consume hunger. Overheating causes nausea and slowness, prevents bathing benefits, and leaves these penalties for 90 seconds after exiting. Leave the bath before overheating.

Undiluted single-type waters provide level I effects for up to 5 minutes.

Undiluted single-type acidic water removes all harmful effects. Mixing and dilution can reduce the cleansing chance and the number of effects removed.

Cooking onsen eggs

Place an Egg Basket directly adjacent to hot spring water at 60°C or above.

Right-click with normal, blue, or brown eggs to add them. Colors may be mixed, with a maximum of 16 eggs total.

Cooking takes 5 minutes of active heating while the area is loaded. Finished eggs automatically pop out of the basket.

• Shift + empty-hand right-click retrieves uncooked eggs in their original colors.

• Adding more eggs resets the cooking timer.

• Removing suitable hot water pauses cooking; restoring it resumes cooking.

• Ordinary water, lava, and decorative water over floor slabs do not heat the basket.

Building a bathhouse

Decorations include floor tiles and slabs, wall tiles, bath stools, bath buckets, showers, taps, mirrors, stone and wooden outlets, dragon outlets, noren curtains, bamboo clothes baskets, and bath ducks.

Important equipment notes:

• Bath Buckets and Bath Stools: half-height decorations; two can be stacked in one block space. Bath Buckets do not collect water.

• Showers and taps: right-click to switch decorative flow on or off. They do not