Fluids, Water Physics & Evaporation

Water is the single most important resource in Timberborn. Understanding how the fluid simulation works is essential for designing efficient dam networks, planning reservoir placement, and surviving droughts. This guide covers the core physics of water flow, evaporation, contamination, and storage.

How Fluids Work in Timberborn

Timberborn uses a full 3D fluid simulation system. Water is not simply a flat plane; it has real volume and flows dynamically across the map based on elevation differences. Each tile on the map can hold a certain amount of water, and excess water flows outward toward lower tiles. Water sources (rivers) continuously generate water at a set rate, while the edges of the map can act as drains. The simulation runs in real time, meaning water levels shift throughout each day and respond to player-built structures like dams, levees, and floodgates. Channels and aqueducts can redirect flow across terrain that would otherwise block it. The direction of flow is always governed by gravity: water moves from higher elevation to lower elevation, and it will always seek the lowest available path.

Water Depth and Pressure

Water depth is measured in units that correspond roughly to tile height. A tile that is fully submerged holds 1.0 unit of water per layer. Water depth determines whether certain buildings can function: water pumps require a minimum depth of about 0.3 to operate, and deeper water yields faster pumping rates. Depth also affects navigation, as beavers cannot swim through water that is too deep without appropriate paths or platforms. Pressure plays a role behind dams and levees. When water accumulates behind a dam, the depth creates pressure that pushes water outward if any gap exists. Floodgates allow you to control this pressure by selectively releasing water. Understanding depth and pressure is critical for designing multi-level reservoir systems that store large volumes of water in compact spaces.

Evaporation Mechanics

Evaporation is one of the primary ways water is lost from the map, especially during droughts. Every exposed water tile loses approximately 0.045 units of water per day to evaporation. This rate applies per tile of exposed surface area, meaning that wide, shallow pools evaporate far more quickly than narrow, deep reservoirs. During droughts, river sources stop flowing entirely, so evaporation becomes the dominant force reducing your water supply. The key insight is that minimizing surface area is the best way to reduce evaporation losses. A tall, narrow reservoir with the same total volume as a wide, shallow lake will lose significantly less water per day. Covered structures like water tanks eliminate evaporation entirely for the water stored inside them. Planning your water infrastructure around evaporation rates is one of the most important long-term survival strategies.

Contamination Spread Through Water

Badwater sources generate contaminated water that spreads through the normal fluid simulation. Contamination mixes with clean water when the two come into contact, and the resulting mixture retains a contamination ratio based on the volumes involved. Even a small amount of badwater mixing into a large clean reservoir will taint the entire supply. Contaminated water damages crops, harms beavers who drink it, and kills trees and plants it touches. The contamination spreads downstream following normal flow patterns, which means a single badwater source upstream can threaten your entire settlement. To protect against contamination, players can build levees and dams to isolate badwater channels, use floodgates to control when contaminated water is released, or construct water treatment facilities (available to certain factions) to purify tainted supplies.

Badwater Weight and Behavior

Badwater behaves similarly to clean water in terms of flow physics, but it has a slightly higher weight. This means that in situations where clean water and badwater meet, the badwater tends to settle toward the bottom of a body of water while cleaner water stays near the surface. This density difference can be exploited in advanced reservoir designs where intake pumps draw from the surface layer to get cleaner water while contaminated water sinks below. However, the mixing effect still occurs over time, so this separation is not permanent. Badwater sources typically activate during droughts or on certain map configurations, and managing their flow is one of the key challenges in mid-to-late-game scenarios.

Water Storage Calculations: Tanks vs Reservoirs

There are two primary methods for storing water: open reservoirs built with dams and levees, and enclosed water tanks. Open reservoirs are cheaper to build and can hold enormous volumes, but they lose water to evaporation from every exposed surface tile. A 10x10 reservoir that is 3 tiles deep holds up to 300 units of water, but loses roughly 4.5 units per day (100 tiles multiplied by 0.045 per tile). Water tanks, on the other hand, store a fixed amount of water (typically 30 units for a small tank and 90 units for a large tank) with zero evaporation. The trade-off is that tanks require significant building materials and take up footprint space. For long droughts, a combination of deep reservoirs (to minimize surface-area-to-volume ratio) and water tanks (for zero-loss reserves) provides the most reliable water security.

Tips for Minimizing Water Loss

Build deep rather than wide. A reservoir that is 2 tiles wide and 5 tiles deep loses far less water to evaporation than one that is 10 tiles wide and 1 tile deep, even if both hold similar volumes. Use water tanks for your emergency drought reserves since they lose nothing to evaporation. Place dams strategically to create narrow, deep channels rather than broad lakes. Use floodgates to release water only when needed rather than letting it flow freely. During wet seasons, fill your tanks and deep reservoirs first before allowing water to spread across low-priority areas. Monitor your water levels regularly and compare them against your colony's daily consumption to estimate how many drought days your reserves can sustain. Finally, consider placing water pumps at the deepest points of your reservoirs so they continue operating even as water levels drop during extended droughts.