News & Blogs

Yacht Water Treatment – What Chemicals Should You Keep Onboard?

Jun 14, 2024

Importance of Yacht Water Treatment

Water Treatment on Yachts is critical due to the limited access to fresh water sources and the need to store water for extended periods while onboard. The process involves various stages: from filtration, purification, and disinfection, to eliminate pathogens and contaminants, to continuous monitoring and regular analysis. Water systems on yachts need to have regular treatment to guarantee that there is no build-up of harmful organic material, viruses, bacteria, and biofilm.

Yacht Water Treatment can be a complex process that involves the use of several chemicals to treat and maintain water quality. This article discusses the essential chemicals you should keep onboard to ensure your yacht’s water supply is clean, safe, and drinkable all season long.

Superyacht at night

Yacht Water Treatment – What Chemicals Should You Keep Onboard?

Ensuring the quality and safety of drinking water onboard yachts is a top consideration for the health and wellbeing of all passengers and crew. The presence and growth of organic materials in water tanks can lead to health problems. When neglected, this will affect the taste and odour of water. Not only that, but the accumulation of biofilm in the yacht’s pipes can lead to water system problems. Good thing is that this can be solved by the water treatment process.

Why Treat Water on Yachts?

    Here are the top reasons why regular yacht water treatment with chemicals is necessary:

    • Health and Safety: Prevent waterborne diseases by making sure that the water is free from contaminants and microorganisms, making it safe to use and consume.
    • Odour and Taste and Improvement: Water treatment aids in removing unpleasant tastes and odours, making the drinking water clean and pleasant to consume.
    • Corrosion Prevention: Efficient Water Treatment wards off corrosion in the yacht’s plumbing system. This also maintains efficiency of the water system and extends its lifespan.

    Glasses Onboard

    Essential Chemicals for Yacht Water Treatment

    Yacht water treatment becomes more effective when the right chemicals are used. There are a lot to choose from, so here is a quick overview of what they are, where to use each onboard, and their applications. Each of these chemicals onboard must be carefully monitored using the proper water testing kits, to make sure their levels and applications are correct. Residual sterilisation should be measured and logged on a weekly basis.

    Cleaning and Disinfectants

    Hydrasil Ag+

    Hydrasil Ag+ is a registered biocide certified fit for human consumption.

    • What It Does: As an advanced disinfectant, Hydrasil Ag+ specialises in eradicating biofilms and sterilising drinking water. It’s especially effective against legionella, making it a critical addition to your yacht’s water treatment arsenal.
    • Benefits: Eco-friendly and potent, Hydrasil Ag+ breaks down into oxygen and water post-use, offering a greener alternative to traditional chlorine-based products while still ensuring water safety.
    • How to Use It: Ideal for treating water tanks and distribution systems, it should be incorporated into regular water treatment routines to maintain a sterile water supply.

    Hydrasil Ag+

    Chlorine (Sodium Hypochlorite)

    • What It Does: Chlorine was the standard chemical for disinfecting yacht water supplies, however due to its shortfalls, it is rarely used except for shock treatment hypo chlorination or sewage systems.
    • How to Use It: Available in liquid form, chlorine’s concentration needs to be carefully monitored to ensure safety and effectiveness. Utilising proper testing equipment is recommended to maintain the correct levels.

    Chlorine Neutraliser Chemical

    • What It does: Chlorine Neutraliser Chemical is used at the end of a Hypo chlorination application. The recommended contact time according to the WHO Ships Guide to Sanitation is 12 hours. The HCE17 is then added to the tank and pulled through the entire system, this will neutralise the chlorine completely, making the water safe to dump.
    • Benefits: It is against regulations to dump water with a 50ppm solution of chlorine. This product means that the tanks do not have to be flushed as many as three time to remove the chlorine making a large environmental impact. The system is put back into use in a safe rapid way.

    HCE17® Chlorine Removal Chemical

    Hydrogen Peroxide

    • What It Does: Hydrogen peroxide is a very volatile chemical and is not suitable for use in freshwater systems, it should only be used in wastewater treatment.
    • How to Use It: Ensure it is stored in a dry, well-ventilated area away from flammable materials. Its application varies based on the specific needs of the waste system being used.


     After water oasses through a Water Maker, it is stripped of many essential minerals. To help to balance this the water should be passed through a remineralising filter which will add a small amount of minerals. An even better solution is to have an injection system using a liquid mineral solution such as Octo Mineral+.

    Octo Marine Mineral+

    Scale and Corrosion Inhibitors


    Phosphates are used to protect the yacht’s water system against scale and corrosion. They contribute to the protection of pipes and fixtures, as they create a protective coating within the pipes. This coating serves as a defence against the accumulation of scale and the dissolution of metals, maintaining the efficiency and integrity of the water system onboard.

    Ensure that it is a food grade product such as Multitreat PS corrosion inhibitor

    pH Adjusters

    Elevated pH levels lead to diminished efficacy of disinfectants such as chlorine in pools and spas, high pH levels can also cause skin and eye irritations.

    In order to maintain a balance, the correct PH plus or minus should be used, these are available in powder and liquid forms.

    Check Octo Marine’s Pool Spa Treatments.

    Octo Marine Multitreat PS

    Best Practices for Chemical Storage and Handling

    Handling chemicals onboard requires proper knowledge on how to store them. Keep chemicals in a cool, dry place away from direct sunlight. Label them properly to avoid misuse and potential accidents.

    Always use proper protective gear whenever using any form of chemical. Make sure to follow the label’s instructions and warnings in order to use them correctly.

    In addition, regular monitoring of Chemicals Onboard must be observed. Have a regular schedule of water quality testing so as to know if adjusting the chemical dosing is needed. If you need further help with this process, take advantage of our Water Testing Service.

    Handle With Care


    Maintaining a safe, clean, and effective water supply onboard yachts requires an extensive approach to Water Treatment, including the use of various chemicals outlined in your water safety plan. By understanding the usage and application of each of these chemicals, as well as implementing best practices when using them, yacht owners and operators can ensure the health and safety of everyone onboard. Keep in mind that the key is not just adding chemicals but adjusting and monitoring the treatment process to maintain optimal water quality throughout the season.

    As leaders in the yacht water treatment industry, get in touch today if you have any questions about any of our chemicals, and we will do our best to assist you.

    More From Us