Many boaters are concerned with the water quality coming from their boat water tanks, and with good reason. Getting a waterborne illness on a boat is too easy, and questionable water is everywhere. It’s hard to have confidence in a system with many challenges: questionable water sources, dock pipes that are not properly pressurized, using dirty hoses at fill-up, dirty tanks, dirty water lines in your boat, and stagnant water in your tanks.
Still, I’m always surprised when I see boaters lugging around 36 packs of bottled water. Folks who weekend on their boats seem to rely on bottled water. I acknowledge the convenience, but there’s got to be a better way.
I’m not an expert on water filtration, but the goal isn’t hard to achieve: drink the purest water you can get. Here are a few alternatives for anyone needing drinking water on their boat, from afternoons or short weekend getaways to living aboard full-time (at a dock or anchor).
Keep Your Boat’s Water Tanks Clean
No matter how you use your boat, keeping the tanks as clean as possible is a good idea. Even if you just use the water for dishes or rinsing off, it’s not fun for that water to develop a nasty stink.
Boaters who winterize their boats will also want to clean their systems well after recommissioning in the spring.
Sterilize Your Tanks
You should sterilize your boat’s water system regularly, and anytime you suspect any funk in the tanks or lines. This includes whether you just bought the boat or it has been sitting unused for a while.
The process is similar to shocking a swimming pool: Fill the tanks full with super-chlorinated water and let it sit overnight. Run each tap until you smell the chlorine, so it sits in all your water lines, too. It’s best to bypass your hot water heater because the chlorine isn’t great for the metal heating elements. Let the chlorine sit overnight, and then drain the system completely empty. Then, fill it with clean water.
You want to use plain, unscented household bleach to shock your system. I’ve looked online to find how much bleach to use, but the numbers are all over the place.
My best guess would be one cup for every 30 gallons of water. This is the typical advice for RV systems, which are the same as boat systems.
Chlorox recommends 1 cup for every 9 gallons of water, which is significantly stronger.
That’s a very strong shock for a seriously dirty system. If I were just doing routine maintenance and had no problems, I’d probably go with half that, but that’s just me.
Remember, these numbers are for shock-cleaning the system, not for use after fill-up. This is too strong to use regularly; you must empty this water out and refill the tank with clean water.
It’s also a good idea to open the tank and take a peek inside occasionally. That’s the only way to be sure how clean it is and to ensure there are no sediments or algae growth.
Use the Right Hose
Potable water hoses are usually white and made differently than regular garden hoses. You can find them at any Wal-Mart or hardware store in the RV section. If you plug your hose in permanently at the dock, you need a white one. But it’s a good idea to have your own clean hose, even if you just fill up your tanks occasionally. The hoses at fuel docks are the worst since you have no idea what they might have been used for or how long they’ve been sitting out. Some boaters may have used those hoses to purge their blackwater systems during pumpout!
If you only use your hose occasionally, make sure to drain it completely after each use. You don’t want water sitting in the hose, growing all sorts of disgusting things, while it is in your hot lazarette locker.
🛒 Shop on Amazon — Camco Drinking Water Hose 50′
Let the Dock Water Run Awhile
Most marina water lines are used only for washing boats. Few people will drink that water, and most marina managers can’t even imagine someone doing so. I once worked at a marina that regularly received warnings from the health department about not sanitizing the water lines properly and having much bacteria in its well.
You want to flush out whatever nasty water has been sitting in the dock water lines for a while. If you see your neighbor washing their boat, you’re probably okay. That water is probably disgusting if you’re the first to run the hose in a week or two. Run the hose for a good long while. Better yet, use it as an excuse to wash the boat before you top your tanks.
Treat Your Water
The next step is to ensure that the tanks stay clean. You need to add a small amount of chlorine bleach to the water to keep it sanitary in the tanks. This is a fail-safe if all your previous steps have failed to catch something nasty.
I usually skip this step if I’m at a dock and dealing with good-quality city water. That’s only if we go through a few tank fulls a month and things keep flowing. If it’s going to sit, I’ll add the bleach.
How much bleach should you add to each tank? According to Chlorox, one teaspoon for every 7 gallons of water is the correct dose. For a 50-gallon water tank, this comes out to be just over two tablespoons (or about two capfuls).
To ensure that my cooking and drinking water don’t taste like bleach, I use charcoal filters (both under-sink and a filter pitcher) — more details below.
Ways to Get Drinking Water Without Resorting to Disposable Bottles
If you go through all these steps and keep the system clean, most boaters could be drinking from their boat water tanks. But there are other factors to consider. What if you only live on the boat for a few days and a month, and it sits empty the rest of the time? The water system will be harder to keep clean with the pumps off and stagnant water in the tank. What if you stay at a marina with bad water, like the dirty well water you sometimes find in the Chesapeake? Then you have no choice but to fill up elsewhere or bring your water from the city.
Here are a few options for getting good-quality drinking water without using individual disposable plastic bottles.
1 or 2.5-gallon Water Bottles
One solution is to buy a bigger bottle of water at the store. Instead of 36 bottles, buy two or three 2.5-gallon jugs. Then, use them to refill glasses or a reusable water bottle. This way, you can also use good water for cooking and making coffee or tea.
2.5 or 5-gallon Refillable Jugs + Handpump
Refillable, reusable hard jugs, like those that go on an office water cooler, are an even better, cheaper solution. You probably don’t have an office water cooler in your boat, but you can purchase small handpumps that snap on the top. Then, just set the bottle on the floor and use the water to refill reusable drinking bottles or your coffee pot.
You can get the plastic jugs in small 2.5/3 gallon or standard 5-gallon versions. You can exchange the standard ones in supermarkets, big-box stores, office suppliers, and hardware stores. The exchange is between $6 and 7.
An even cheaper way to fill them is with a refill station. Most Wal-Marts have a Primo water refill station. Just bring your bottle in, refill it, and you’ll pay something like $2 at checkout. The refill stations are reverse osmosis filters; most have charcoal and UV sterilization filters. Ultimately, you get exactly what you would in disposable bottles, but it’s much cheaper and more convenient for the boat. You can get the handpump at most Wal-Marts or on Amazon.
🛒 Shop on Amazon — 5 Gallon Jug Handpump
Counter-top Gravity-feed Purification Filter System (Berkey type)
We used a large Berkey countertop filter system to filter water with good results back in the day. Several brands now make the same thing, and they’re more easily available on Amazon than directly from Berkey.
This might be a good option if you are traveling on your boat and can’t trust the tank or marina water fills. You could filter your tank water through this filter for drinking and cooking. Finding water fills and buying water bottles isn’t practical on the road.
The system uses very fine “black carbon” filters, so it works very slowly but filters very well. They used to claim that it could make nearly any water source safe to drink. I don’t know if that’s true, but if you start with safe water, it will certainly make it taste fine. They are very effective filters and use no power, so they can easily be used on boats. Their biggest problem is their size and the fact that you need someplace to secure them so they don’t fly around.
We found other solutions in the long run, but if I had a house, I would likely use one to filter tap water for drinking and cooking (especially if I were on well water).
🛒 Shop on Amazon — Glacier Fresh Gravity Water Filter
How to Filter Your Tank Water for Safety and the Best Taste
If you live aboard your boat, it’s far more practical to keep the water system spotless and use the tap water for washing, cooking, and drinking. Still, you’ll want to remove any bad tastes left by chlorine treatments or boat smells, so here are a few options to finish it off for drinking.
In-line RV Hose Filters
These filters are the easiest to use, but I’m dubious about their effectiveness for boaters.
If you plug the hose into your boat’s system, this is a good way to get extra filtering. However, I would still opt for something that filters your drinking water right before drinking it.
Camco and other RV companies sell better in-line, multi-stage filter setups for this purpose. The filter housings on these use standard sizes, making it easier and cheaper to get replacements.
We have used them when filling our tanks, but they’re less than ideal. First, they dry out over long periods if you use them that way, giving critters and algae time to grow in there. And they’re only rated up to a certain flow, which I bet most boaters exceed when filling up. If you are filling your tanks, I think there are better options.
🛒 Shop on Amazon — Glacier Fresh In-line Hose Filters
Watermakers
If you have a watermaker, it produces the cleanest, purest water you’ll find anywhere. Watermakers should be making water at about 200-300 ppm, whereas most city docks we’ve seen are 400-500 ppm. We’ve also seen 1,200 ppm at some marinas that have dirty wells. We test the water with a portable tester like this one on Amazon. Most watermaker owners carry one of these.
If you have a watermaker, there are times you won’t want to use it. If you’re staying during hurricane season in a marina, spending time up a river, or in a gross harbor, most boaters don’t want to turn it on and clog the prefilters. During these times, you’re stuck with what you can get elsewhere.
If you use your watermaker, the product water gets mixed in with your tank water like anything else. In this case, you still need to follow all the precautions about keeping your tanks clean and shocking them occasionally. However, I generally don’t add much extra chlorine to the tank after running the watermaker.
Since we constantly deal with different sources of water, we still run all our cooking and drinking water through finishing filters.
Pitcher Filter
Charcoal filter pitchers have always helped with one thing: removing any traces of funky tastes from chlorine or boat tanks. But they’ve come a long way recently, and we love our new two-stage filter from Life Straw. In addition to a charcoal filter for taste, it also includes an ultra-fine pleated filter to eliminate sediments and larger objects. It claims to be good enough to get rid of most bacteria and other germs, too, something the old Britas and Purs could never do.
We started with a glass version from Glacier Fresh, which didn’t last long even though I was very careful. The BPA-free plastic version from Life Straw Home uses the same filter set and fits nicely on our counter.
The small charcoal filters last two months, while the pleated filter lasts six. In the long run, I think it’s cheaper than the old Britas.
🛒 Shop on Amazon — Life Straw Home Water Filter Pitcher
Generic Undersink Filter
If you clean your tanks and keep them as close to sterile as possible, all you need to have drinkable water is a simple charcoal filter to get rid of any nasty tastes from the bleach. Household under-sink filters are designed to tap into your faucet’s cold water line.
They’re easy to install and work fine with any electric pressurized water system. We used it successfully off a 2.0 gpm pump (about the smallest you can get) but upgraded to a 3.0 gpm, and it works much better now. If there’s not enough pressure in the system, filters clog faster and must be replaced more often.
There are several ways to install the under-sink filter, but we chose Culligan’s EZ-change filter system. My only problem with that system was the cost of the filters and how hard they were to get (they must be ordered via Amazon). We have since replaced this with an even simpler in-line filter for refrigerator ice makers (found off the shelf in The Bahamas). You could also install an on-faucet filter, but we have a pull-out faucet, so this doesn’t work for us.
🛒 Shop on Amazon — Culligan Undersink Filter
UV Light Sterilization
Charcoal filters don’t sterilize water, so if you want the highest level of safety, an under-sink UV filter system is for you. We looked for one that would work with a boat’s 12-volt electrical system, which is challenging because they often sell for over $1,000 and are designed to work with a home reverse osmosis system.
Eventually, we found the Acuva ArrowMAX 2.0. This system is designed for RVs and includes a simple in-line sediment/taste filter and a UV light. It needs to be wired for 12-volt power, but it only draws power when pumping water. The power draw is negligible compared to your water pump.
We got ours on Amazon. Unfortunately, it’s no longer available there, but you can purchase it directly from Acuva.
Putting It All Together — How We Keep Dulcinea’s Tanks Fresh and Clean
That was a lot of information, so here’s a quick breakdown of how we do it on Dulcinea. We’re not experts, but we are picky, and this system works for us.
- We shock-treat the tanks once or twice a year with chlorine bleach.
- We avoid fill-ups outside of major cities to avoid well water. When in doubt, I will use my portable water tester (Like this one on Amazon).
- We use our own drinking water hose, which we try to keep as clean as possible.
- We run the water at the dock for a while before we top our tank.
- We fill the tank and add a small amount of chlorine bleach to keep it clean.
- We filter all drinking and most cooking water through our 12-volt Acuva UV filter system.
- Drinking water then goes through a countertop Life Straw Home filter pitcher.
The result is water that never has chlorine, tank taste, or odor. It’s probably overkill for most boaters, but it works for us.
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