Why Does My Turtle Tank Lose Water?

Wood Turtle

One of the major problems that aquatic turtle owners face is water evaporation from their tank. The reality is that for some this can mean losing an inch or two between water changes, but for others it can mean up to a third of their tank water disappearing. So why does this happen and is there anything that can be done about it?

Why Does Tank Water Evaporate?

We all know that water evaporates when it is warmed. So in the case of a tank of water, it will usually evaporate quicker when there is substantial difference between its temperature and the air. There is other as well though, including air that is very dry or a strong moving current in the water (caused by filtration).

The climate in which you live will determine how quickly the water evaporates. If the air temperature is quite warm and dry, you will find that your tank loses water fairly quickly. Those living in temperate climates tend to find that the water in their tank evaporates more quickly in the winter when the central heating is on.

Is Water Evaporation a Problem?

It is important to be aware that it is only pure water that evaporates and any of the other substances in the water will remain there. If you are losing a lot of water regularly then, this will have an effect on water’s chemical balance. It is essential then that you address the issue by topping up the water levels as frequently as possible.

Mississippi Map Turtle
Mississippi Map Turtle

Some turtle keepers place a marker on the exterior of the glass upon filling the tank. This allows them to see how quickly water is evaporating and offers a quick guide when topping up the water levels.

The thing to remember when topping up the turtle tank water (indeed, when filling the tank at any stage) is that it is best to use dechlorinated water. In addition to this, store the water at room temperature for a few days before adding it to the tank. This will ensure that the tank’s water temperature does not drop too much too quickly.

If the tank is losing a lot of water, it might be worthwhile having a bucket or watering can with room temperature water at the ready.

If keeping a bucket of room temperature water nearby is going to be a problem due to space or young children, you might want to think about using an automatic refilling pump. An automatic refill system will have a dosing pump connected to a reservoir with sensors that detect a drop in the water level and then refill it to the required level. This is a much easier way to keep the water at the required level and will help to avoid any dramatic changes in the chemical levels of the water. Amazon sells a selection here if you’re interested (opens in a new tab).


Losing water from a turtle tank is a common problem, with external environmental factors determining how much water is actually lost. To combat this, regular water top-ups are required; for ease, an automatic refilling pump can be used. This will help to keep the water’s chemical levels balanced and, as a consequence, your pet healthy.

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I am a content creator by profession but exotic animals are one of my great passions in life. Over the course of my adulthood, I have had the pleasure of looking after stick insects, terrapins, an Egyptian tortoise, giant African land snails, a crested gecko, a Chilean rose tarantula, a couple of curly-haired tarantulas, and a selection of millipedes, centipedes and worms!

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