Helping shipowners to save gallons of water

Ships carry a lot of water. According to one estimate, AIDA Cruises’ AIDAsol requires one million litres – more than 264,172 gallons – of fresh water every day for its 1,000 passengers and crew. This potable water is used in kitchens and laundries, for swimming pools, and for bathrooms and restrooms throughout the liner.

On larger ships, such as those carrying 5,000 to 6,000 passengers and crew members, the amount of water used per day can jump up to about 500,000 gallons. These are huge volumes of water, and water costs money in many different ways. Not only is there the actual cost of the water, but because water is heavy it adds considerable weight to the ship, which can increase fuel costs while the ship is at sea.

A gallon of water weighs slightly more than eight pounds. That means that a larger ship needs to carry as much as four million pounds of water to meet the needs of the ship and its passengers for just one day. And that’s not the end. Water that is flushed from a toilet or urinal typically goes into a blackwater holding tank, where it is stored until the ship docks. In most cases, emptying the blackwater tanks is also quite expensive, especially because those costs have steadily risen in the last decade. Ports outside the US see it as a revenue stream.

And communities, at least here in the US, that are frequented by cruise liners are starting to get concerned about all the water these ships need. According to an article in the Sun Sentinel , which serves the Broward, Palm Beach and Miami-Dade areas of the US, “these floating cities…take more than 300 million gallons of South Florida’s water every year.”

That article was written on 28 November 2011 at a time when South Florida was experiencing a water shortage. While conditions are better now, future droughts are likely in this area and other areas of the country that cater to cruise ships. As a result, any steps that can be taken to reduce water consumption will help local communities in need of water, while decreasing operational costs for the cruise lines.

The Sun Sentinel article refers to these giant liners as floating cities and that is essentially what they are. So one initiative we can take to reduce onboard water consumption is to look at what some land-based cities are doing to reduce water consumption. One key area where consumption can be reduced is in cabin bathrooms and public restrooms.

The first step involves performing a water audit similar to those that have become very common in office buildings, schools and other large facilities on land. A water audit can involve all water-using fixtures, but if shipowners were to audit bathrooms and restrooms, they would need to look at the:

• Number of toilets and urinals onboard
• Number of sinks and taps
• Age of the toilets, urinals and taps as this can indicate how much water they consume)
• Any leaks that were detected 
• Malfunctioning fixtures or mechanical failures.

Older and malfunctioning fixtures can be a serious problem. Very often a toilet or urinal is designed to use a specified amount of water per flush, but with time, use and some abuse, they often consume far more. To combat this, shipowners should set a time limit as to how long to keep these fixtures. Most owners and building managers consider making these changes every seven years in land-based facilities because it allows them to take advantage of new water-using fixtures that reduce water consumption. A similar practice would help shipowners.

When updating or replacing older toilets and urinals, shipowners should know that, once again, what works on land likely will work at sea. For instance, like owners of land-based facilities, shipowners could opt for one of the following water-saving technologies:

• Tank inserts: A displacement device is placed in the storage tank of a conventional toilet to reduce the volume of stored water. 
• Dual-flush toilets: These devices enable the user to select from two flush volumes
• Pressurised and compressed air toilets: These systems use compressed air to aid flushing by propelling water into the bowl at increased velocity, while at the same time using a relatively small amount of water. 
• Vacuum-assisted flush toilets: A variation of a conventional toilet, the fixture is connected to a vacuum system that assists a very small amount of water in flushing.

When it comes to urinals, cruise ship owners have more to consider. Different urinal models offer the possibility of really making a dent in water consumption. On land, the average urinal uses about 30,000 gallons of water per year and is used three times more often than a toilet. That’s a lot of water, so in places like South Florida, California, and areas in the western half of the US where droughts are a problem, many building owners have decided not to select urinals that use water, but to select no-water urinal systems. This is because no-water urinals offer significant water savings, cost the same or less to install than traditional urinals, and they don’t have mechanical parts. These systems also help reduce blackwater emptying charges because no water is used.

For a land-based facility, more water is typically used in restrooms than in any other area of the facility. The only exception is if the building is heavily landscaped. However, the steps addressed here can still make a significant impact on reducing the amount of water used and stored on ships, which has cost savings written all over it.

Klaus Reichardt is CEO of Waterless Co