Three Reasons Your Boat Needs a New Sanitation Device


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It's crucial to understand the environmental impact that boats can have on our oceans and waterways. Improperly managed sewage discharge from boats can introduce harmful pollutants and bacteria into our marine ecosystems, posing a significant threat to aquatic life and human health. 

The US EPA VIDA (Vessel Incidental Discharge Act) addresses this issue by establishing new regulations for managing incidental discharges from vessels, including sewage. As a responsible boat owner, it's important to ensure that your marine sanitation device (MSD) works correctly and complies with VIDA's current regulations. By doing so, you can help protect our oceans and waterways for generations to come.


Your MSD is a critical piece of equipment designed to treat and discharge sewage safely and compliantly. A properly functioning MSD keeps you and your crew safe and sanitary and helps you avoid costly fines from the Coast Guard and other regulatory agencies.

However, there may come a time when you need to replace your MSD instead of fixing it. Even high-quality MSDs have an expiration date, and updating or upgrading your system regularly is crucial for the health and safety of your vessel and crew.

Here are some signs that it's time for an MSD upgrade:

  1. Maintaining your current MSD is more expensive than getting a new one.

    While you may be tempted to troubleshoot and fix your old MSD to save money, replacing individual parts like the regenerative blower or discharge pump can be costly and time-consuming. Moreover, there comes a point when replacing old parts will no longer make the system work like new. It's best to consult with an MSD expert to determine whether maintenance is effective or whether you need a new system.
  2. You've outgrown your current sanitation system.

    MSDs are rated for a specific volume of use, and if your operation has grown significantly since the last time you updated your system, you might be overloading it. This can lead to blockages and harm the system. You must consider whether your current system can handle your growing needs.
  3. It's time for an upgrade.

    If you've been waiting to buy an MSD, more durable options may be available now. For instance, a carbon or stainless steel model will be more resilient to hot and cold temperatures, making it last longer. When buying your next system, consider upgrading to a bigger size or better material so your investment will last for years to come.

    If you need a new MSD, the first decision you must make is its size. To determine the right size, you must consider factors such as the number of people on board, hours of use, required certifications, and types of waste the MSD will handle.

    Just as there are a wide variety of vessels and offshore rigs, different types of marine sanitation devices suit various boats. Having the wrong MSD might seem trivial, but that's not true. Having the wrong MSD can result in:
    • Overloading your system (leading to smelly, unsafe conditions)
    • Coast Guard fines
    • Frustrating and time-consuming maintenance projects
    • High replacement costs

Fortunately, finding out which type of MSD would best suit your vessel is relatively simple. 

The Different Types of Marine Sanitation Devices: What You Need to Know

According to designations set by the U.S. Coast Guard, there are three different types of marine sanitation devices. 

Type I 

Type I marine sanitation devices consist of an onboard treatment device through which the sewage you generate can flow. As the sewage flows through, it is treated so that you can safely discharge the byproduct off your vessel. 

This type of marine sanitation device takes a physical approach to treating sewage. A Type I MSD pulverizes and macerates all sewage it pipes in. The resulting mass is then disinfected with specialized chlorine tablets. These tablets neutralize the sewage, reducing the levels of harmful bacteria it hosts to safe (and Coast Guard-approved) limits. 

Sometimes, a Type I marine sanitation device might use electrodes to speed up and enhance disinfection.

Once the sewage mass is safe, a Type I marine sanitation device will discharge it from your vessel (as long as that is an accepted practice in the area). Type I MSDs are typically found on smaller recreational boats—ones that are 65 feet in length or smaller. 

For larger vessels, we turn to another class of device. 

Type II

Type II marine sanitation devices are also flow-through devices: Sewage is deposited in one end of the sewage treatment system, piped through, treated, and then discharged off your vessel. This type of system is excellent because you don't have to hold sewage sludge on your vessel for long. 

Type II MSDs differ from their Type I counterparts in how they treat sewage. Whereas Type I MSDs take a physical approach to treatment, Type II MSDs rely on biological or aerobic digestion of the waste. Oxygen-dependent bacteria break down the waste, which is then treated with a disinfectant. 

Wondering what sets this type of device apart from Type I devices? Bacteria-enabled biological treatment often produces lower bacterial levels than Type I physical treatment—making it easier to meet Coast Guard standards for safe discharge and less likely to face fines. These MSDs are common on larger commercial boats and production platforms because they're efficient at what they do. 

Type III 

Type III marine sanitation devices are more straightforward than the previous types. These MSDs consist of a holding tank that prevents the overboard discharge of untreated sewage. Because they're less complex but less effective at treating waste, they are usually appropriate only for smaller recreational boats.

Marine CZ three _side view

Need Help Determining Which Type of MSD Is Best for You? 

When choosing an MSD for your vessel, you need to make the right decision. Doing otherwise could lead to steep fines and excessive maintenance, ultimately forcing you to replace your system. Save yourself that trouble and pick the right MSD for your vessel the first time around. 

To make choosing the ideal marine sanitation device easy, check out H2O LLC's easy-to-use online calculator.

H2O LLC is a trusted manufacturer of high-quality, long-lasting, and high-performance MSDs. They can help you find the best device for your boat that is compliant with the current US EPA VIDA regulations. Contact their knowledgeable team today for troubleshooting, pricing, and more.