Water is a precious resource on a boat, especially during extended trips or when sailing in remote areas where resupply may not be possible. Efficient freshwater management not only ensures that you have enough water for drinking, cooking, and hygiene but also helps maintain the boat’s systems in peak condition. Here’s an in-depth look at managing freshwater usage, including filtration, treatment options, and maintenance practices.
It’s A Long Journey To Your Boat
The first step to having fresh water on your boat is getting it onto your boat in the first place! There are three main ways that boats obtain fresh water. Direct connection to shore water, Filling onboard storage tanks, and Watermakers.
For this article, we will deal with shore-based water supplies. Watermakers are a complex topic and we will cover that in a future article.
Dock Water
Whether you hook up your boat directly to a shoreside water source or use the shoreside water source to fill up your freshwater tanks, there are several factors that need to be kept in mind when it comes to water quality. The source, how it gets to your boat, where it’s stored in your boat, and distribution once it’s on your boat. We’ll cover each of these in detail.
The Source
Some marinas use a public water source that is treated. In the United States, public water is generally considered safe to drink as it is regulated by the EPA and must meet strict standards for contaminants, meaning most people can drink tap water without concern; however, water quality can vary depending on location. While generally safe, some areas may have higher levels of specific contaminants due to local geological conditions. The age and quality of the distribution pipes that bring the water to the marina can be a factor. Some systems, especially older ones, still have pipes and solder joints that can leach lead into the supply.
Some marinas, especially those in rural areas, use a private well as the water source. Water drawn from wells can be affected by local contaminants and groundwater infiltration and, in the case of marinas, may be subject to leeching from the water source you just booted in on. Well water quality is rarely tested regularly once the well has been established.
While most well sources offer excellent quality water, the water is usually untreated and frequently unfiltered so that it can contain sand and other particles. A flood event, construction in the area, and agricultural activity can impact the quality of well water without anyone being aware.
Getting Water To The Dock
In looking at many marinas you will see that the water distribution system on the dock is PVC pipe. PVC (polyvinyl chloride) pipe is generally not considered safe for drinking water as it can leach chemicals into the water supply, making it not recommended for potable water lines; it’s typically used for drain, waste, and vent lines instead.
Docks systems can be extensive. Our home marina is small, but we still have over 1,500 feet of 2″ waterline serving the docks. I’ll spare you the math, but that’s around 250 gallons of water. Those water lines are exposed to the sun like many are, and the water heats up. In the summer here in Florida, I can get 90º water out of the tap when it’s first turned on. That heated water is sitting in those pipes, festering for days or weeks depending on how many people are washing their boats at any given time. The farther you are from the shore, the worse the problem can be.
One final consideration is leaks. The water lines in dock systems may have many joints, especially floating docks with many side piers. These connections can be underwater for part or all of their life. Go to many tidal marinas and look at the connections from shore to the docks for power and water, and you’ll see huge clumps of marine life clinging to and potentially eating into the hoses and cables. The joints in these pipes can leak, causing the water they are sitting in to leech into the supply when water is running through them.
The last leg of the water’s journey to your boat is the hose you use to connect your boat to the tap on the dock. Make sure that the hose you are using is drinking water-safe. Typically, these will be white in color and clearly labeled on the package. Many people use expanding hoses as they are convenient and easier to store. We do! Many of these hoses, especially cheap ones, contain lead in the fittings and use petroleum rubber for the hose material rather than food-grade silicone. Make sure to check that they are rated safe for drinking water.
The takeaway is to remember that the water in dock water systems may have been sitting in less than ideal conditions, in pipes not necessarily designed for drinking water, for extended periods of time. Even if the marina is connected to a crystal-pure water source, by the time it reaches your boat, it may be old and contaminated.
Getting Water Into Your Boat
In general there are two methods fresh water is brought onto your boat. The first and most common is filling storage tanks. Most cruising boats have storage tanks that will hold from 40 to 200 gallons of fresh water. These tanks are typically stainless steel, polyethylene, or, in rarer cases, fiberglass or aluminum.
These tanks are filled from a shore water source, and the water is then pumped with a pressure pump to the taps on the boat. Some boats also have a shore water hookup that allows water from the dock to flow directly into the boat’s water system, bypassing the tanks so that you use dock water directly.
Direct Shorewater Connection
While convenient direct shore water connections should be used with caution, first, make sure that you use a pressure regulator. Some water systems can have high pressure or experience sudden pressure surges. These can burst onboard hoses or pop off connections, causing a flow of water into your boat. Unlike a leak from your onboard tanks, shore water is pretty much a limitless supply, and it’s not unheard of for a burst water line to sink a boat. If you leave your boat, even for an hour or so, it’s recommended that you turn off the shore water connection to prevent an unfortunate leak from sinking your boat.
Filtering Dock Water
Regardless of whether you directly connect to shore water or use the shore water to fill your onboard tanks, it is highly recommended to filter the water supply. Filters will prevent sand and other particulates from entering your onboard system and remove many contaminants. The small hose-mounted filters are about the minimum you’ll want to use. These carbon filters will do a fair job of removing the big bits and some of the chlorine and chemicals.
If you don’t use your water for drinking or cooking, this is probably enough. If, however, you drink or cook with the water from your tanks or shore-based water, you may want to consider a larger one or two-stage filter system.
Boaters who frequent the Bahamas and the Caribbean may want to consider permanently installing a water filtration system on their boat that includes a UV sanitizer, as the quality of water in those areas is known to be questionable.
Water Treatment
Treating your onboard water is important to maintain the water quality in your tanks. Especially if your boat is not used regularly, or in the warmer months, your water tanks can easily become a mini-ecosystem of plants and bacteria. Many a boat owner have been greeted by sulfur-smelling water after their boat has been sitting for some time. The sulfur smell in water is usually caused by the presence of hydrogen sulfide gas, which is produced by bacteria that break down organic matter in the water. Adding a water tank additive (usually chlorine-based) will help to keep algae and bacteria from forming in your water tanks.
If your boat has been sitting with water in the tanks for a month or more, you may want to flush your tanks and give them a “shock treatment.” This involves draining the tank as fully as possible, adding a high-dose chlorine treatment, letting it sit for a few hours, then draining and rinsing the tanks. When doing this be sure first to turn off your water heater to avoid damaging it when draining your water system. Then, ensure that you run water through every tap on your boat, both hot and cold, to flush out the lines. Hot water lines are more prone to the build-up of bacteria due to the constant presence of warm water.
While you can use standard bleach for this process, we recommend using purpose-made treatments. Off-the-shelf bleach may have other cleaning chemicals and fragrances or be of questionable purity. Most marine and R/V dealers sell fresh water treatment and shock-treatment products that are purpose-made for drinking water systems. Always read and follow the manufacturer’s directions. Chlorine is an acid; too high a dose can damage pumps, hoses, and fixtures. The typical dosage is about 1-3 parts per million (ppm).
Point Of Use Filtration
If you use water either directly from a dock source or from your onboard storage tanks for drinking or cooking, you may want to use a point-of-use water filter. These can either be installed in your water lines after the water comes in from either your tanks or outside, an under-the-counter water filter similar to those used in kitchens, or a water filtration pitcher such as a Brita filter. These will help to remove contaminants that may have developed in your tanks, made it from the dock, or leached in from your onboard plumbing. They will also help to reduce the chlorine and taste from water tank freshness chemicals.
On Kissed Some Frogs, we use a combination of filters and bottled water. First, we choose to drink bottled water. We filter all of our water as it comes into the boat with a standard hose-type carbon filter and treat the water in the tanks with commercial freshwater treatment.
Our boat was built in 2006, and we have plastic tanks with unknown BPA levels. Our boat spends most of its time in Florida, where it gets pretty hot in the summer, potentially allowing bacteria and algae to grow in our tanks and lines. We have a carbon filter installed just after our freshwater pump to filter the water after it leaves our tanks. We also use a Brita Water Filter pitcher for any tap water that we might use for coffee or cooking. We feel that it gives us the best overall water quality and health protection.
Efficient Water Usage Practices
Now that you have the best quality of water coming out of your taps, here are a few tricks to help minimize your water usage. For most cruisers in the USA, unless you spend long periods at anchor, water conservation is not a big concern. You can pull into just about any marina and top off your tanks, and if you stay at a marina, you have an almost limitless water supply. We say “almost” because, on our last Great Loop, we noticed a few marinas that have started to charge for water hookups. One or two were metered, and a few added a flat fee per night, similar to how electric usage is charged.
Here are a few tips on how to conserve water.
1. Short Showers:
- Time showers to no more than 2-3 minutes. Wet your body, turn off the water to lather up, and then rinse off quickly. Consider using a low-flow showerhead designed for water conservation.
2. Improve Efficiency:
- Equip sinks and showers with aerators to maintain a good flow while minimizing water output.
- Consider using ‘camping wipes’ or no-rinse soap products for personal hygiene to reduce water use. Just don’t flush them!!!
3. Fresh Water Flush Toilets:
- If your toilets flush with fresh water from your water tanks, this can be a major drain on your water supply. Limit the number of times you flush your toilet. Consider the advice of Captain Chris: “If it’s brown, flush it down. If it’s yellow, let it mellow.” Men, especially those of us a bit older who may go frequently, may consider using a porta-johnny during the day and flushing once the bottle has filled rather than every time. This will also take some of the load off of your black-water tanks.
4. Onboard Laundry
- While convenient, onboard washers and dryers use large amounts of water. Surprisingly, many dryers use more water per cycle than washers as the water is used to cool and condense the moisture out of the warm dryer air rather than venting it to the outside. Most marinas have laundry facilities either on-site or nearby. Consider using those instead of your onboard equipment. You’ll get a better clean from the larger machines, it will dry quicker, and it’s a great way to meet your fellow boaters!
Maintenance of the Pressure Pump
Without your pressure pump, unless you can get shore water pressure, you are out of luck! Most boaters don’t think about their pressure pump until, mid-shower, it stops working. Pressure pumps don’t need a lot of maintenance, but checking on them from time to time will keep them trouble-free for longer.
First and foremost, when you leave your boat for any length of time, it’s important to switch your pressure pump off. Two things will happen if you have a leak in your freshwater system. First, you will empty your fresh water tanks into your boat. Depending on the leak’s location, it could just dump into the bilge, and the bilge pump will take care of it. If it’s inside a cabinet, it could damage the cabinet and flooring. Second, it will probably burn out the pump motor or wear out the pump diaphragm or impeller. Turning off your fresh water pump when the boat is not in use is a quick and easy way to help prevent problems.
1. Regular Maintenance:
- Inspect the water pressure pump regularly for leaks and check the condition of hoses and connections. Replace worn or damaged parts promptly to prevent further issues.
- Listen for unusual noises from the pump, which may indicate air in the system or failing components.
- Most water pumps have a filter to protect the pump from debris. It’s important to clean these periodically. Calcium buildup, algae, and other debris can clog up the filter.
2. Pressure Settings:
- Ensure the pressure switch is set correctly according to the manufacturer’s specifications to avoid excessive cycling and potential damage.
- Pressure Accumulator Tanks are installed on many boats. These tanks store pressure so that your pump doesn’t short cycle Rrrrr-rrrrr-rrrrr-rrrrr when you use water, causing undue wear on the pump and increased battery usage. The pressure tank will let the pump run longer, building up a pressure reserve. You’ll know if you have a pressure tank because there will be a delay before the pump starts when you turn on the tap. Also, the pump may continue to run for a few seconds after you turn off the water. These tanks contain a rubber bladder that stores the pressure and need to be charged periodically with a bicycle pump. As the weather gets warmer or colder, the pressure in the tank can change. The tank usually has a label, letting you know what the pressure should be. Check it with a tire pressure gauge and adjust it as needed.
(Next to pump on right)
Keep The Water Flowing!
Proper management of freshwater resources on a boat requires a combination of filtration, treatment, and efficient water use practices, along with regular maintenance of water systems. By adopting these strategies, you can ensure a sustainable water supply and enhance your boating experience. Whether you’re crossing oceans or enjoying coastal cruising, a well-managed water system is key to a successful voyage.
What is your biggest onboard fresh water challenge?
Let us know in the comments below! 
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