How Do Cruise Ships Not Run Out of Water?

By Robert Palmer

Cruise ships are massive vessels that can accommodate thousands of passengers. These floating cities offer a wide range of amenities and services, including swimming pools, restaurants, and even ice skating rinks.

However, with all these facilities comes the need for a substantial amount of water. So how do cruise ships not run out of water?

Water Desalination
One of the primary ways that cruise ships ensure they have access to enough water is through desalination. Desalination is the process of removing salt and other minerals from seawater to make it safe for human consumption.

How does desalination work?

Desalination typically involves two stages: pre-treatment and membrane separation. During pre-treatment, seawater is filtered to remove larger particles such as sand and debris. In the membrane separation stage, semi-permeable membranes are used to separate salt and other minerals from the water.

Reverse Osmosis

Reverse osmosis is one of the most common methods used in desalination. In reverse osmosis, seawater is forced through a semi-permeable membrane at high pressure. The membrane allows water molecules to pass through but blocks salt and other minerals.

Water Recycling
Another way that cruise ships conserve water is through recycling processes. Wastewater generated onboard undergoes various treatments before being reused for non-potable purposes such as cleaning decks or flushing toilets.

What is wastewater treatment?

Wastewater treatment typically involves three stages: primary treatment, secondary treatment, and tertiary treatment. During primary treatment, large solids are removed from wastewater by gravity settling or filtration.

Secondary Treatment

In secondary treatment, biological processes are used to break down organic matter in the wastewater further. This stage may involve using microorganisms such as bacteria to consume organic matter.

Tertiary Treatment

Tertiary treatment is the final stage of wastewater treatment and involves removing any remaining contaminants from the water. This stage may involve using chemical processes such as chlorination or filtration through activated carbon.

Water Conservation
Cruise ships also take measures to conserve water by reducing consumption and preventing unnecessary wastage. This may involve installing low-flow showerheads, aerators on faucets, and implementing policies that encourage passengers to reuse towels and linens.


In conclusion, cruise ships have multiple methods of ensuring they do not run out of water. These include desalination, wastewater treatment, and water conservation initiatives. By utilizing these strategies, cruise ships can continue to provide passengers with an enjoyable experience while minimizing their environmental impact.