Question: Does nuclear consume too much water?

Answer: Water isn’t consumed in the way most people think about it. It is warmed and returned to where it came from. A small amount is turned into clouds and rain.

The amount of cooling water used by a nuclear plant is slightly more than the amount used by a similar capacity coal plant.

A big misconception is the term “water consumed.” But calling that water “consumed” is misleading.

In reality, the vast majority of water withdrawn for cooling is returned right back to the source.

For example, a large nuclear station using a once-through cooling system might pump on the order of 4.6 billion litres of water per day from a lake or ocean, but about 99% of that is returned to the source after it passes through the plant​ Only around 30 million litres per day (a tiny fraction) is actually “consumed” – mainly through evaporation​. In other words, over 98% of the cooling water goes back to the river or sea it came from​^[1].

So when you see huge numbers for water use, remember that almost all that water isn’t “used up” at all – it’s just “borrowed” for cooling and then given back, slightly warmer but still water.

Regulators ensure that the returned water is released in an environmentally safe way (for example, not too hot). So the idea that nuclear would “consume” huge volumes of our limited water is inaccurate. Most of that water goes right back where it came from.

The only significant water intake a nuclear plant needs is for the cooling process (condensing the steam). This is an important reassurance: the core operation of a nuclear plant runs on a closed water cycle. We’re not continuously feeding it new water like an endless sponge. The plant’s water demand is almost entirely about condensing steam efficiently,

Question: How do nuclear power plants use water?

Answer: They use steam to create electricity, and then they turn the steam back into liquid water. Nuclear plants don’t have a special thirst for water. They use water in much the same way as other coal power stations, and we’ve already managed those in Australia for decades.

Nuclear power plants, like coal-fired plants, use heat to boil water into steam, which spins a turbine to generate electricity.

The water used within a nuclear reactor to transfer the energy and drive turbines to generate electricity. The water circuits within the plant are filled when the reactor is commissioned and maintained through the life of the reactor. The much larger use of water is for cooling and condensing the steam to create the pressure difference to drive the turbines..

That means if a site had enough water for a coal power station, it can likely support a nuclear station too.

Associate Professor Edward Obbard of UNSW points out that all seven Australian coal plant sites proposed for reactors have sufficient water supply for nuclear, and his colleague Prof. Fiona Johnson adds that nuclear water requirements are “not substantially different” to coal – “if we have managed that sustainably within the catchment then I don’t think there is a particular concern”​.^[2]

If coal plants have been using water on a large scale, replacing some of them with nuclear plants wouldn’t suddenly break the bank on water.

Question: What if there isn’t a good water source nearby?

Answer: There are cooling options for every location.

Australia is a big continent with a wide range of climates and water availability, and the good news is that nuclear cooling methods can be tailored to local conditions. There’s no one-size-fits-all requirement that would limit us. Engineers can choose from a variety of cooling strategies, including:

• Coastal or Seaside Sites can use abundant seawater for once-through cooling. This is common internationally. For example, in the UK, all nuclear plants are recommended to be on the coast to take advantage of ocean cooling​.
• Rivers and Lakes. Even once-through returns ~99% of water.​ A cooling pond or reservoir could be created to give the plant its own dedicated water body. There are flexible ways to manage the warmer water effects, including cooling canals or combining with existing dams.
• Cooling Towers (Closed-Loop): For inland sites or where we want to minimise water withdrawals, wet cooling towers are the go-to. They dramatically cut down how much water needs to be taken in from the environment (by cycling the same water).
• Air Cooling (Dry Cooling): In very arid areas or to avoid using much water at all, it’s possible to use air-cooled condensers (essentially giant radiators) instead of water-based cooling. This is exactly what some outback Australian power stations have done – for example, Queensland’s Kogan Creek and Millmerran coal plants use dry cooling systems that cut water usage by over 90%​. At Kogan Creek, they achieved extremely low water consumption (around 0.2 litres per kWh of electricity, versus 2–3 L/kWh for typical wet-cooled plants) by using huge fan-driven radiators​.^[3] This option means that even in Australia’s driest regions, one could in theory run a nuclear plant with minimal water.
• Hybrid Systems: Some cooling setups combine air and water cooling, or switch modes seasonally to save water. For instance, a plant might use mostly air cooling but spray a bit of water in extreme heat, or use cooling towers plus an air-cooled section. These hybrid designs give flexibility to balance water savings and efficiency.

^[1] https://world-nuclear.org/information-library/current-and-future-generation/cooling-power-plants

^[2] https://www.abc.net.au/news/2024-07-20/nuclear-power-plant-water-supply-environmental-concerns-nsw/104084348

^[3] https://world-nuclear.org/information-library/current-and-future-generation/cooling-power-plants