How Often Should You Pump Out a Boat Holding Tank?

Quick Recap

• Depending on tank size, people on board, usage habits, and trip length, you may need to empty your boat holding tank weekly, biweekly, or monthly.
• Pay attention to the tank’s gauge and the flushing action on board to check the fullness of the tank.
• Speedy Septic provides professional boat pump-outs.

Your Pump-Out Schedule Depends on How You Use the Boat

Owning a boat is lots of fun, but as any mariner knows, there’s plenty of maintenance involved in keeping your craft seaworthy (or lakeworthy). One key task is keeping up with a boat pump-out schedule.

A boat’s holding tank’s job is to store all waste and sewage on board. Staying on a pump-out schedule can prevent a range of smelly issues during your next day on the water. Learn about your boat’s holding tank, how frequently to empty it, and when it’s time to call a pro for help with the job.

What Is a Boat Holding Tank?

When your boat’s marine head (toilet) is used, the waste has to go somewhere. Dumping waste in bodies of water is typically strictly regulated, so it goes into a boat holding tank, which is essentially a septic tank for the boat. The tank eventually fills up, so it must be emptied out periodically.

How Frequently Does Your Tank Really Need Emptying?

The general rule for how often to empty a boat holding tank is to wait until it’s three-quarters full. This ensures efficient suctioning during pumping without the risk of an overflow. The frequency depends on your usage and how many people are on the boat. For a typical couple, this may take seven to 14 days, while others report only needing a boat holding tank pump-out every four weeks.

What Determines How Quickly the Tank Fills?

Determining how long a boat holding tank lasts before needing to be emptied depends on a few factors.

Holding tank capacity

Your boat sewage tank will fill up faster if it’s on the smaller side. Most tanks range between 10 and 40 gallons, and the average person generates about three to five gallons of waste and flush water per day.

Number of people on board

The more people on board, the sooner you’ll need a boat septic pump-out. Using the figure of three to five gallons of waste per person, per day, you can do a rough estimate on how quickly your tank will fill.

Trip length and overnight use

Your marine head will see more use on longer trips or overnight voyages. Be sure to factor in this additional use when determining how quickly your tank will fill.

Toilet and flush-water usage

Another factor to consider is how much water your toilet uses when you flush. Although marine heads are more water-efficient than toilets on land, some still use quite a bit of water when flushing, which tends to be the main contributor to a full tank.

Whether the tank gauge is accurate

Your tank should be equipped with a gauge to measure the capacity, but these may become inaccurate over time. That’s why checking the gauge is a key part of marine holding tank maintenance.

Boat type and usage pattern

Your boat type determines the type of holding tank, the flush water mechanics, and the number of people you’ll have on board, which all affect how quickly the holding tank fills. Make sure you know your craft inside and out to ensure a proper boat sewage pump-out schedule.

How Can You Tell the Holding Tank Is Getting Full?

Along with reading the wind and knowing how to use a compass, knowing the signs that a boat holding tank is full is a key skill for any sailor. Here are the top signs to know:

• Tank monitor reads as three-quarters full or higher
• Slow or difficult flushing
• Sewage smells from outside hull vent line
• Liquid seeping from vent or tank connections
• Physical changes to the tank, such as expansion or bulging

Should You Pump Out the Tank After Every Trip?

Depending on the size of the tank, the number of people on the boat, and the tank’s capacity, you may need to empty your boat sewage tank after every trip. Ten-gallon tanks generally hold a day’s worth of waste for two people, while larger tanks can accommodate larger crews and longer trips.

What Happens If You Wait Too Long?

What happens if you wait too long to empty your holding tank? Failing to empty it on time can lead to a number of unpleasant consequences, such as:

• Liquid waste squirting out of hull vent fittings.
• Spilled waste staining the hull.
• Raw sewage entering waterways, putting you at risk of prosecution under environmental law.
• Foul odors.
• Clogging vents, causing difficulties during pumping.
• Waste solidifying and hardening.

Can You Leave Waste in a Boat Holding Tank?

Waste can be safely left in a holding tank for some time. Though we don’t recommend leaving it for long periods (as it can compact and harden), you can generally leave waste in the tank for days at a time. The only possible issue is if the odor becomes noticeable, though there are products available that can help with this issue.

Where Should Boat Waste Be Pumped Out?

To empty your tank, you’ll need to use a marina pump-out service. Most marinas have one of these systems in place, and they’re able to suction the waste out of your holding tank and into either a municipal sewer system or a septic tank on land.

When Should You Schedule Professional Pump-Out Service?

Like septic pumping and other septic system maintenance tasks on land, some jobs are better left to the professionals. While many boat owners are comfortable pumping their own tanks, there are times when it makes more sense to choose the professional, eco-friendly pump-out services provided by Speedy Septic. Consider hiring a pro if:

• Your tank is extremely full.
• It’s been more than one to three months since your last professional pump-out.
• There’s hard or compacted waste clogging the tank.
• It’s the end of the season and you’re winterizing the boat.
• You plan to store the boat for a long period.

Speedy Septic Can Help With Boat Holding Tanks

At Speedy Septic, we work on septic waste systems of all kinds, including those on boats. We provide fast, reliable, and eco-friendly marine holding tank pump-out services, ensuring total removal of all waste so you can get back out on the water with confidence. Contact us today to learn more or to schedule a septic service on your boat.

Frequently Asked Questions

We strongly advise against leaving sewage in your holding tank over winter. The waste can harden and compact, making it very difficult to fully clean out when it’s time to take the boat on the water again.

You can legally empty your boat’s holding tank at a marina pump-out station or with the assistance of a mobile pumping service. Dumping within three miles of the US coastline (or virtually any other waterway in the country) is strictly prohibited.

You can reduce odors from your marine holding tank with eco-friendly liquid enzymes and other specialized products. You should also pump regularly to avoid odors from occurring in the first place.