Watermakers are great…but they are also expensive, use a ton of electricity, take up a lot of space, and are a royal pain in the neck to maintain.
Just another damned thing to spend time and money on when we could be sailing our boat or out enjoying the places we sailed to1.
Given that, although we did think of installing a watermaker several times in our three decades of cruising, we resisted. Admittedly, a decision that was made easier by the 250 US gal tank capacity of our McCurdy and Rhodes 56.
The downside of not having a watermaker, aside from the obvious, is the danger of gastro disruptions we can get from bad water. And when out cruising it’s often hard to figure out the quality of what comes out of that hose on the wharf.
In fact, over the years I got two intestinal parasites that required treatment from dock water. (Phyllis, being of the stronger gender, shook both off without trouble.)
Anyway, nothing like a three-month tummy ache to get one motivated!
What to do?
Filter may be sufficient when you have a 250 gal tank. But if you need to trade tank space diesel versus water, a water maker is the choice. I like your filter. There must be more cost effective alternatives available?
Hi Erik,
I have never seen a less expensive one that does the same job of taking out bad pathogens. If I knew of one I would have mentioned it. If you find one I’m all ears.
Google NSF P231 to learn about certified pathenogen removal filters. There are quite a few, including the Argonide P231 CoolBlue system that uses standard housings and cartridge sizes. I believe NSF/ANSI maintains a listing of certified systems.
The unavoidable problem with RO systems is the high pressure; if there is a tiny leak anywhere in the membrane or seals, there is a large driving force. Yes, they can remove salt, but not the salt that slips through leaks. The average filtration is very impressive, but the absolute filtration not always perfect. There can easily be a few percent bypass.
Hi Drew,
The Argonide looks good but I think probably not capable of filtering the entire water supply?
At 0.5 gpm, it’s an under counter solution, not whole water supply.
Hi Mark,
Yup, that was my thinking. One of the benefits of the large Seagull is that it seems to get all the bad stuff out, but still has a good flow rate and will pass a lot of water before it blocks up.
We had a problem with a tainted water tank and lines on our RV and used the following process which involves mixing colloidal silver from a health food shop and hydrogen peroxide (preferably 5-6% strength) from a chemist. For each liter of tank water, add 2ml of colloidal silver and 2ml of hydrogen peroxide to a quarter bucket of water, mix and then add to a nearly full tank. Only mix what you can use immediately. At this point it’s good to go for a quick sail to stir everything up and dislodge any biofilm. Ensure breathing holes are clear to release air bubbles created by the reaction and then run all the taps to flush the lines. After treatment, drain and flush the tanks with clean water. We then used a silver/activated carbon filter B.E.S.T Water Filters | Australia’s B.E.S.T. RV Water Filter – B.E.S.T. Water Filters for all water added to the tanks regardless of source which served us well during the next 7 years touring and also the past 3 years cruising.
Hi Bryan,
Sure, that sounds like a good decontamination process. Problem is that when cruising, particularly in remote places, if we were to rely on decontamination we would be going through that repeatedly, and then how would we know whether or not the next fill was bad? No way to know. So yes, decontamination has its place, but it’s not a solution.
As to the BEST, it looks good, but I would strongly doubt that given it’s size and price that it would be capable of taking out all significant pathogens, including from large quantities of water over time, as the big SeaGull can.
Hi John,
Think of the Best filter more as a cost-effective way to kill any nasties in the water with silver ions not as a filter to stop them hence its small size. The activated carbon part is also very effective at removing chlorine so for those with water-makers who sometimes fill tanks onshore there is less of a risk of damaging the reverse osmosis membrane when flushing.
Hi John, might I ask how you used to disinfect the tank and lines on your aluminum yacht?
My OVNI (with aluminum tank), I scrub with normal dish washing soap once a year, and replace the small seagull filter whenever I can get one.
They seem to be impossible to get new cartridges for in Norway, so I haven’t managed for some time, so I must admit I have run over a year on the same cartridge.
I am quite meticulous about how I fill, but with just 400 liter capacity, I can’t go forever. In Norway, clean water is easy to get (from a dock or a river), but still, I like the idea of disinfecting stuff, but I don’t want to destroy the aluminum. Plus I’m currently sailing further abroad.
Kindly, Arne
Hi Arne,
Yes, that’s an issue with aluminium tanks and is a lot of the reason we went over to filtering every drop. We tended to clean in the same way you do, although it is worth knowing that an ocational flush with chlorine in the water will not hurt aluminium (according to Drew) as long as it’s well flushed out afterward.
I find marine-spec gear much more expensive than equivalent home or commercial gear. I’m not sure I understand what spec justifies the extraordinarily high price of the referenced filter system.
Looking at a store I’ve used before (for a high-end coffee filtration system), I found the following system that seems to be at the same or higher spec, but is in the $500 range vs $3000 range.
https://www.freshwatersystems.com/products/kineticopro-kpmf-hc620-mp-nanosmart-series-20-filtration-system?variant=42116695228600
Maybe I missing something on the spec for the marine-grade system?
That’s a 1 micron system, while the Seagull systems that John referenced are 0.4 micron. Apples and oranges. I’m not opining on whether the KineticoPRO is or isn’t good enough, just noting that it isn’t the same as the Seagull.
Hi Tom,
Well first of the Seagull is not specifically marine. They sell a lot to out of the way homes and RVs. Second I don’t think the filter you link to is the same or even close. Note the qualification word “help” in their claims. “help remove microbial cysts, chlorine, chloramines, trace pharmaceuticals,”
I would bet that was inserted by some lawyer. And note too that NFS 42 says nothing about pathogens “Filters are certified to reduce aesthetic impurities such as chlorine and taste/odor.”
Do as you wish, but having had two gut bugs that required treatment this is not a product that I would be selecting by price. General Ecology make very specific claims with no qualifications, and given that they have been in business for decades I think said claims are almost certainly accurate, otherwise they would have been put out of business years ago.
“has been independently tested and documented to meet the EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers against bacteria, cysts, and viruses”
I have used the smaller (Seagull), under sink unit for two years now on our 35′ cruiser. We are mostly weekend warriors with some one week summer cruises from NY to New England. Our two 35 gallon steel tanks are clean and the Seagull water filter makes our water taste like spring water. I use the foot pump for the filter water and the electric pump for non filtering. My concern was more for drinking water and not having to carry bottled water. It’s funny to watch other boat owners faces when I offer them some “tank” water! They are surprised on how good the water taste. and bonus, the coffee tastes great!
I used a standard 9″ carbon filter that fits inside a standard 9″ filter housing.
These are very inexpensive.
I just checked and 9″ carbon filters appear to be available in 0.5 micron.
If i filled with suspect water then i also filtered the water as i filled with a similar filter.
These can handle full domestic flow rates will handle the largest cruising boat.
I also dosed suspect water with chlorine as i filled (not good for aluminium tanks i think but i had stainless).
7 years cruising filling from a variety of good to definitely suspect. No gut issues and great tasting water.
Nature-Pure QC2 (Quick Change) system by General Ecology Inc. Says it is a .4 micron. See Practical Sailor article. Defender.com sells them.
Sensitive subject. Our watermaker has been in use for 7 years with no service issue other than properly changing the water ingress filter regularly and winterizing properly, and we never fill the tank with any other source of water . However, I am concerned with your statement that the watermaker does not filter all potential hazards as well as your solution. Could you elaborate on this. Thanks in advance.
Hi Patrick,
I’m not an expert, but I do know that when we installed a small drinking water RO system here at our cottage the very knowledgable water expert we hired cautioned us not to rely on it to remove all pathogens, and I understand the same is true about larger systems, whereas the Seagull seems to be certified to get rid of all bad stuff and our first hand experience would seem to support that.
It’s not so much that an RO watermaker might allow pathogens through. (It won’t, unless it’s broken, in which case it’ll also let salt through.) Rather, the issue is that an RO watermaker provides no protection against anything that is introduced to (or grows in) the tank downstream of the watermaker.
With a full-flow UV system like the one at my house, the tank is upstream of the sterilizer, and everything downstream of the sterilizer is small-diameter pipe. The flow rates are fast and the water does not linger. Worst case, if you’ve been away for a few days, you run the tap for 30 seconds and now everything from the UV to the tap has been totally flushed thrice over.
With a point-of-use filter like the tap-mounted Seagull, or a whole-system filter like the Seagull that John put on his tank outlet…. same situation. The pipes are small, water does not linger there, and they get flushed with every use.
An RO watermaker dumps water into a tank while it’s running, and then that water sits there for days or months. The tank is never fully flushed. So you get one E.coli sitting there in the seam of a gasket and you fill the tank with perfectly clean RO water. An hour later you have two E.coli. By the end of the day there are 16 million of the little bastards. Next week, assuming they haven’t run out of gasket residue to eat, there are 3×10^50 of them.
That’s why we don’t rely on RO *upstream of a tank* as the sole drinking water safety system.
RO at the point of use *can* be a good way to remove virtually all pathogens, but there’s always the possibility of a cracked O-ring or a cracked RO membrane allowing something to seep through. Since it’s hard to reliably defend against those failures, it’s unwise to treat point-of-use RO as the sole line of defence.
Hi Matt,
My understanding is that both viruses and possible some bacteria can make their way through an RO membrane, so I don’t think it’s quite that simple. I googled around quite a bit and it seems that most authorities agree that viruses can get through, and some claim bacteria too. Here’s one: https://doulton.in/water-filters-india/does-ro-purifier-kill-viruses-bacteria-in-water/
The are many more opinions on the internet for those who wish to parse them.
Anyway, good point about RO water siting in a tank.
Since this is a boating site, I assume we’re only considering the kinds of RO membrane that are used for desalination. (There are other kinds for other purposes that have larger pores and are not as effective on salt or on small viruses.)
Desalinator membranes have a pore size on the order of 0.6 nm or less. ( https://www.sciencedirect.com/science/article/abs/pii/S0376738810010045 )
The smallest viruses have a capsid diameter on the order of 15 nm. ( https://www.sciencedirect.com/topics/immunology-and-microbiology/extra-small-virus ) The smallest bacteria (M. genitalium) are around 200 nm. It is physically impossible for any of them to make their way through the RO desalinator membrane.
The RO membrane also removes a lot of the stuff that microbes need to grow in the treated water ( https://www.sciencedirect.com/science/article/pii/S0043135420308538?via%3Dihub ).
The reason why many vendors and authorities say “don’t rely 100% on an RO to eliminate all bacteria and viruses” is that it is very difficult to be certain that an RO system is working perfectly. Do you have micro-fractures in the membrane? A cracked O-ring? There’s no way to be certain without tearing the thing down for inspection under a microscope, but if those flaws exist, then some pathogens (and some salt) could bypass the membrane entirely.
Safety systems always use a “Swiss Cheese” model. Any one piece of cheese has holes that a hazard can get through. Layer enough pieces of cheese and, eventually, you can be 99.999% certain that none of the holes will overlap. Maybe the airplane has a crack in a turbine blade, and that made it through a hole in the “X-ray inspect all the blades” layer of protection. But it eventually gets caught by the “40 sheets of kevlar wrapped around the turbine case” layer of protection.
When you use an RO membrane as your sole layer of biological protection for water safety, you have none of that redundancy. It will remove all viruses and all bacteria, as long as it’s working perfectly, but it can break in ways that could let small amounts of pathogens (and salt, and other contaminants) through and that you might not immediately notice. Those pathogens then grow to potentially dangerous quantities in the storage tank downstream of the RO unit.
When engineers and health officials come across cases like this, we don’t tell the public “This thing makes your water 100% safe as long as it’s working, but here are 15 ways it can break that are hard to inspect and might make it not safe.” Rather, we just say “This thing is not 100% guaranteed to make your water safe under all conditions, so you should do these extra steps as well to be certain.”
A filter like the Seagull is made in such a way that most of the likely failure modes are backed up by redundancy in the physical structure of the device. So it is a great second layer of defence.
Hi John,
I am a fanatic about water filtration, both at home and on the boat. Although we have a large capacity of water storage(200 gal., nothing better than a freshwater washdown of a salt-sprayed boat) plus a watermaker. Here are some options that I have successfully used. In terms of a UV system that will only run light once the tap is turned on. https://www.amazon.com/Acuva-Wanderer-Water-Purifier-Boats/dp/B0BMRZ5K7D Also, when we do fill the tanks from outside water sources. https://mobilemusthave.com/pages/water-filtration I was considering the Seagull system, but the price took my breath away.
We have the Seagull IV at our galley sink, and I use a 20 micron filter when filling the tank. We’ve been planning on adding filtration after our FW pump, but we’ve not pulled the trigger yet. This article has made me star to look into it again.
I looked at the Blu Tech link above, and a big difference I see between it and Seagull is the lack of test results. Blu Tech claims 0.2 micron and then provides the following statement:
“The Blu Tech “Off-Grid” Filter is 3rd party tested by IAPMO and certified to NSF/ANSI standards. IAPMO’s water efficiency and sanitation standard is an American national standard. Blu Technology filters are trusted in the industry, and come standard on RVs from some of the biggest manufacturers!”
I’m surprised Blu Tech doesn’t explicitly state the standard they met. I also couldn’t find any mention of which NSF test is met on Blu Tech’s website: https://goblutech.com/pages/main-faqs. They do mention that they’re not yet able to sell in California, Wisconsin, and Iowa yet due to the need of being registered.
Whereas General Ecology provides a link to their test results: https://www.purewateronline.co.uk/wp-content/uploads/2023/09/701017-test.pdf and states that they meet NSF 53-2010.
I’m sure Blu Tech is a fine product. The skeptic in me just likes to see the evidence. The price point of the Blu Tech is excellent compared to the Seagull, but sometimes you do get what you pay for.
Along those lines, there is a Seagull “knockoff” available made by ‘Above Water Systems’: https://abovewatersystems.com/. They also post their test results (NSF 53 and NSF 42): https://abovewatersystems.com/wp-content/uploads/2019/09/Testing.pdf. I haven’t done a direct comparison to the General Ecology filter yet, but I suspect you could buy the AWS case and use a General Ecology filter depending on the test results.
Hi Bill,
I agree. Claiming standard compliance without quoting the specific standard is a huge red flag for me. Much like “studies have proven” which usually indicates that the rest of the sentence is a lie.
We have had the Seagull system for a few years and love it. However, we were going through the $138 filters in about 2 months. We have 1990 sailboat with aluminum water tank. No clean out access at all and no telling how much chlorine has been run through. So, we decided to plumb in our general ecology (same maker as seagull) dockside prefilter just after our fresh water pump. Problem solved. Our tank has a lot of particulate in it and we can not get it out.
Why do you filter the water after it comes out of the tank, instead of filtering the water you put in the tank? With the latter you can remove the chlorine as well.
I also noted that the Seagull system claims to filter 23000 liters. That is a lot of water. It does not seem to take out the chlorine though.
The less expensive filters that are sub micron will last a lot less (often it is not explicitly stated) and will likely have a slower flow.
This filter: https://www.aqualogicfilters.com/Inline-Hose-3/4-C-Ultra-10-INCH claims to go down to 0.01 to 0.03 micron and has activated carbon to get rid of the chlorine (big problem for the aluminum water tank) but it probably won’t last as long. They claim “one year”.
Because of sediment already in the tank that I can not remove, which clogs seagull filter. I filter
With carbon rv inline when filling tank
Hi Maurik,
It would take way too long to fill the tanks through a Seagull and also the filter needs to be kept wet. And finally, even if we filtered every drop it’s still possible to get a pathogen growing in the tank, so better to filter the output. And I’m pretty sure the Seagull takes out chlorine.
That said, we used to use a General Ecology dockside filter when we filled to get the worst of the crap out, as well as the chlorine.
Question John…The advantage of a Watermaker is that it adds freshwater to the freshwater tanks when on a long journey, whereas the Seagull uses the water from the freshwater tanks, thus depleting its volume on a long voyage.
Hi Keith,
I guess I can’t really see that linkage. To me the Seagull is about purification. Where the water comes from is a separate issue governed by a lot of other criteria.
It’s probably more complex than this, but if it comes down to micron ratings then you can get a 0.02 micron system for a few hundred dollars:
https://www.freshwatersystems.com/products/aquacera-ceraguard-purifier-uf-drinking-water-system?variant=17208023777323
But then you should also factor in how long will it take to clog the filter, need for multi-stage filters with different ratings, what the throughput in GPM/LPM is, etc. Also the required pressure to operate; most of these filters need 20+ PSI. Not really useful for filtering water going into the tank from a deck-fill; more for pulling water out of the tank. So then you’d have to consider your tank water “dirty”.
Perhaps more than a “Tip” topic?
Only certified for NSF 42 though. Perhaps they’ve just not paid for NSF 53.
I’m looking now for a NSF 53 filter than can handle 4 gpm that doesn’t cost $3,200 like the Seagull IV X-6. The X-6 just parallels three X-2’s so worst case I can probably jerry rig something.
Hi Bill ,
Hope you find one for less. That said, sometimes something that is expensive is so for a reason: that’s what doing it right, plus a fair profit, costs. My guess is this is the case with the General Ecology Seagull line.
Hi Again, Bill,
Now I have thought about it, it does seem a bit unreasonable that the case for the larger Seagull, in effect, costs about $2400 when we subtract the cost of a filter. Of course there may be costs in there that I’m not aware of such as certification and liability insurance.
I suspect that General Ecology are operating at a *fat* gross margin on those. Their “Dockside Prefiltration System” at $221 appears to consist of a proprietary clear filter housing and a 3 micron cartridge. The replacement cartridge is $63. Meanwhile, similar 1 micron cartridges from Aquaboon are $7 each and fit a standard housing that costs $39 from any of five vendors.
I have to assume that the other products from the same page are similarly marked up.
Hi Matt,
Maybe, but the other interesting possibility, given that no one seems to have found a true lower cost alternative to the Seagull line with the same product assurances is that development and liability insurance make the cost just the way it is, particularly for a low volume item like this.
Here’s another Seagull like ‘knockoff’ with certification for NSF 42/53/401 that is slightly cheaper.
https://www.multipure.com/products/drinking-water-systems/aquaperform/
This company seems to take certification seriously; they are the only company I saw that has a filter with NSF P231 microbiological certification. This one (https://www.multipure.com/products/drinking-water-systems/aqualuxe/) was in the $1000 range but with an output of only 1gpm, much less than the large Seagull.
Here is a good site to check what NSF certifications your filter has:
https://info.nsf.org/Certified/dwtu/
I an always wondering why watermakers take the water from the sea. Why not from air since the water in the air is already desalinatied and while on board air humidity is always high so there is plenty of fresh water in the air. It is much cheaper and requires less power. The hard part has already been done by mother nature.
Energy cost of AWG (Atmospheric Water Generation) is probably at least 300 Wh/l (Watt-hour per liter), depending on humidity, while desalination of sea water is closer to 3 to 4 Wh/l (depends on system and salinity). AWG has almost a factor of 100 higher energy use. The reverse osmosis water makers are actually pretty good at what they do.
Hi Maurick,
Thanks for fielding that, I had no idea.
Hi Berend and Maurik,
This is a more complex comparison than it might seem. You’re both right, in different ways. Sea water evaporated to the atmosphere is almost completely desalinated and mostly clean in other ways too. That moisture can indeed be drawn from the air with zero added energy. Seems perfect, right?
However, airborne water is not completely pure. Rain is quite clean and usually drinkable, can indeed contain pathogens and pollution. In significantly populated areas one would at least need filtration.
The bigger problem is that the method to extract water from air without adding energy is by condensation. That needs air at high moisture saturation, for its temperature, and a surface that the moisture can condense on. The ideal setting is a large metal surface along the edge of a long hill where the wind pushes the lower air mass upwards to cooler height. This is used on the Canary islands. To get a useful amount, we need a significant area. Too much to be practical on a boat. Especially since the right conditions are not present often enough and significantly enough on a boat.
We can still artificially create something that works. A normal compressor dehumidifier does exactly this, blows warm moist air over a cold surface to condense the moisture. The efficiency of this depends on initially not too cool air and higher moisture increases efficiency a lot.
Still, the power input for this latter method will always be significantly more than needed for e good reverse osmosis system.
I don’t think the Seagull system will work with a foot pump, only with a pressurized system. Is this correct? I’d like to add a filter inline with my manual (foot) pump in the galley. Any suggestions?
Tim Sowerby
Hi Tim,
I have never tried, but off hand I can’t see why it would not work with a foot pump. If in doubt, give them a call, I have always found them helpful.
I asked General Ecology and this is the response:
“Thank you for your inquiry.
In response – foot pumps are typically only designed to work against atmospheric pressure. Their limited stroke volume and back flow valves are generally inadequate to overcome the restriction of any downstream filtration device.
You will achieve better performance from our system if you install in a pressurized system or use a manual pump capable of producing greater volume and pressure. (Operating pressure needed: minimum 25 psi; maximum 125 psi.)
Look for a hand pump with a large displacement and check valve to prevent backflow.”
Hi Tim,
Thanks for the fill on that.
I had one with a foot pump. It’s hard work. It definitely reduces water consumption 😉. After a few years with this set up I am taken aback when I go on other boats where they run the tap as if they are at home with an unlimited supply.
Hi Ron,
Thanks for fielding that. Nothing like first hand information.
We installed a Seagull IV system in our Boréal 47 when it was under construction. We also had a SeaRecovery water maker installed. Further, we purchased Seagull’s Dockside prefiltration system. Whenever we fill our tanks from a dock we always use the Dockside prefiltration system ensuring clean water going into the tank… the Seagull IV is installed in the galley… the taste is fabulous. The water straight from the tank is fine having been purified by the dockside prefilter but double purified it is excellent.
With a capacity of 600 L, we do need to use the SeaRecovery system off shore. The watermaker water without the Seagull taste like vomit… horrible… drinkable yes, safe yes, but tastes horrible. Unfortunately, this had to be experienced when our water pump failed in the Bahamas… The watermaker water through the Seagull IV is again, fabulous.
I can’t recommend the Seagull IV any higher. Used in conjunction with the Dockside filtration or the water maker, the water is very nice. The replacement filter for the Seagull IV is $138 US and lasted four of us cruising 24/7 7 – 8 months… I think General Ecology recommend replacing it every 6 months. The Dockside filter replacement is $63 ….
After 40 years of being an airline pilot and having had numerous bacterial and parasitical infections from water…. trust me, this amount of money is worth every single penny.
I do have a question regarding sterilizing the tanks… we have painted aluminum tanks and in the past few Covid years have parked our boat over the winter …. In the spring I would like to clean and disinfect the tanks and heard that flushing with vinegar and water is useless. (maybe harmful to the aluminum?) What about bleach? How much bleach should I used for 300 L (two 300 litre tanks) … and will bleach harm painted aluminum. I am asking post doing this once already… last time I think I added one gallon into each tank and let it sit for 24 – 48 hours and flushed with clean water. Any suggestions for me?
Water is critical to life so if you have to spend a few dollars, it’s worth it.
Hi David,
By far the best authority on cleaning tanks is AAC friend in the comments, Drew Frye. Drew is a chemical engineer and cuts through all the BS to what is actually true. Most of what he has written on the subject is in the Practical Sailor archives. Here is just one of his excellent articles: https://www.practical-sailor.com/systems-propulsion/keeping-water-clean-and-fresh
We use “Zero Water filters” for drinking water from our fresh water tanks. TDS usually stays at zero for months. Relatively cheap and my wife no longer demands bottled water for our costal cruising trips.
Hi John,
Your post and the following comments are a bit eye opening to me, I did not know that people were being this careful with water. My question is, should everyone be looking at this type of filtration or is it something that makes sense for people traveling to places with poor water standards or something like that? I don’t think I have gotten sick from water in drinking tank water for a few thousand days but I may also just have been lucky.
I loosely based our system on something that Drew wrote up a long time ago.
I have had 2 issues with water. The first was with our first cruising boat where we jerry-jugged water out from my parent’s house which has well water. In this case, we found that stuff grew pretty quickly in the tanks and lines but after cleaning adding a small amount of bleach regularly solved that. The other was that I had giardia which was no fun but it was totally unrelated to drinking tank water, it was related to whitewater kayaking where invariably you drink some amount of runoff, this is not uncommon for people who do it.
So if you were in a situation like mine, would you be taking significantly more precautions, particularly with filtration? I am trying to get my head around how comparable this is to other risks that we take with water such as traveling to different places, using stream water with iodine when camping, etc.
I hope this isn’t too off topic.
Eric
Hi Eric,
I had already started the below when your post appeared and we share some questions/observations. We have been to ~~70 countries: Central America, the Med and Northern Europe and the Viking route back to North America, so there has been ample opportunity for bad water.
What we do for all water:
When shore-based water is acceptable:
We use an RV type in hose-line charcoal filter for any water coming into Alchemy’s tanks: mostly for sediment and the charcoal helps with taste.
We have a cannister type (10 inch) filter (Pentek UDS-10EX1) under the sink downstream of the tanks for cold water (meaning drinking): hot water is unfiltered after the tank.
We carry ~~90g in 2 tanks, both stainless steel.
We are usually on-board for long periods of time. When we leave the boat for more than a week or so, especially in warm water/climates, we empty the tanks.
Our tanks have good inspection ports, but I have never needed to clean the insides of the tanks.
We do use anti-freeze, the pink stuff as that has been my habit for decades: I have done so, but have never trusted blowing out the lines with air pressure..
When a watermaker is in use:
Where we swim for bathing, we use 3g per day including a fresh water spritz after swimming in salt water (we are US mid-westerners and still wish to get the salt off). We had a watermaker (small Katadyne) in the Bahamas and Central America and it was a big boon to our comfort. Running it every 2 days for 1 hour met our needs and kept the WM fresh.
Ocean passages, the WM was there for back-up, but with ~~90g we never needed to use the WM.
We found the shore-based water acceptable:
In the Mediterranean we only remember the Balearics as having poor (brackish, but likely safe) water. We did not take on water (and only drank bottled water ashore) in Syria, and Egypt, but Israel and Lebanon were good water. Turkey had excellent water and that is where we pickled the WM and basically have not used it in the last ~15 years. Leaving the Med we had good water in the Adriatic countries and in Spain and Portugal on the way out. Northern Europe had good water every where we went (almost every N Europe country) including the Baltic.
Where we felt a WM was nice to have:
I mentioned the Bahamas and Central America and in small areas of the Caribbean where we sailed (St. Martin and N).
Perhaps we have been lucky, so I will knock on wood, but we have never had a stomach bug from our drinking water and the taste has always been excellent.
My best, Dick Stevenson, s/v Alchemy
Hi Dick
While I haven’t been to as many countries as you I would say ditto to your experiences.
Also, I would mention that wherever one is one should ask around before filling the tanks. Usually the locals will advise you.
Could it be that those of us who grew up outside of towns on farms or in places with slightly dodgy water or in countries that didn’t pump antibiotics into the food chain have an in-built resistance to lurgies that lie in wait in the water supply ?
My main driver in installing a charcoal filter at the water tap has always been for better tasting coffee and tea.
Best Mark, (soon to succumb from a water born disease).
Hi Mark,
I think you may be right about relative immunity. I also think it varies by individual. I have always been sensitive to dodgy water and my father was too. On the other hand Phyllis seems to be able to drink from just about any source with impunity.
Thanks for the thoughts Dick. Also very interesting that your watermaker hasn’t been needed for so long. I have ended several passages in the Bahamas and Caribbean and the crew staying on always treated water conservation just as seriously there as on passage as they were trying to stretch the water that came from the US east coast if there wasn’t a watermaker on board. For boats that take passengers, the tanks can feel bottomless when only the crew is on board but the minute the passengers show up with their normal household routines, a few thousand gallons of water feels like nothing.
As an aside, if you are ever replumbing a fresh water system and your boat’s layout allows it, I highly recommend pitching your hoses so that you can just drain the system. To winterize I simply open 3 valves in the bilge, remove the water filter, open the taps, and run the pump for a few minutes with the whole thing being <5 minutes. It also helps that I plumbed in PEX A with expansion fittings which is about as freeze resistant as exists so if there is water trapped somewhere, it is unlikely to do harm. I have blown out lines but that is a lot more work and a bit higher risk.
Eric
Hi Eric,
While I’m no expert on the matter, I would say that for your kind of cruising your current protocol is just fine, particularly since I’m guessing the town water you normally use will be chlorinated so your tanks are, in effect, chlorinated regularly too.
Our case was very different since we were regularly cruising in Atlantic Canada where most dock water comes from a well, or worse still a pond.
Hi John,
Thanks. Yes, the city water around here is all chlorinated. And the only tank growth issue we ever had was with my parent’s well water which immediately went away once we started adding chlorine.
The tank or 2 of water that we don’t take on locally is often from north of the border but usually bigger places like Shelburne or St. Andrews and I don’t actually know what their source is but I do know the source when filling up in Maine and there are no problems there.
Eric
I don’t think there is any good evidence that ‘a splash in your mouth whilst showering’ is at all likely to cause any illness. Indeed, most travellers’ diarrhoea is probably not from water but from contaminated food. We find cruising the Med that most water provided at the docks is drinkable without any additional filtration or treatment.
Hi Peter,
Maybe, but that’s not what our family MD says. Her thinking, shared after I got a nasty one, was if you get any contaminated water in your mouth at all, you are at risk. And according to her, brushing teeth is the same as drinking it. Keep in mind that here in Norther America, particularly in remote areas, water sources tend to be rather more, shall we say, primitive, than what you are used to in Europe. For example, when cruising in Newfoundland, we are really excited to find a water source that is not brown with tannin meaning it came from an open pond with little or even no treatment.
Also note Eric Klem’s comment above, which would seem to support the splash in the mouth argument. That said, I agree that generally when traveling contaminated food is perhaps an even bigger risk, although a lot of relative risk depends on where you are.
To each their own. I love my high capacity watermaker. Maintenance is a non-issue. Eight years (five full-time) and the original membranes still output 120-170ppm. We have a carbon filter between the tanks and the tap. Regular showers keep the Admiral happy.
A few thoughts:
Seagull does not have NSF P231 ratings for pathenogen removal. Many others do. It’s a good product, but that bothers me a bit.It’s a good product, but strong marketing hype has really been key to their success.
Other P231 certified pathogen removal products use industry standard cartridges. That could have cut the cost to a few hundred dollars. I don’t love proprietary systems that lock you in to a single source of refills.
Unless I am not up to date, there is no WHO, EPA, or other government recognized protocol for treating water with silver and H2O2. I believe chlorine (and its analogs) or chloramine are the only recognized treatments. I wish there was. If there is, please post it. This would be a boon to aluminum tanks.
Finally, based in WHO’s experiences and several reports on WHO field workers, water only constitutes a portion of the exposure risk. There is also food from markets and restaurants, unless you never eat ashore and bring everything from home. Also people. Even perfect water does not protect against all risks. But it helps.
Hi Drew,
Thanks for coming up on that. No one I know knows more about this than you do, given all your years of testing at PS on top of your professional qualifications. Do you have a suggested generic alternative to the Seagull?
No one would be happier than me if there was a less expensive, but just as good alternative.
Up until then I will go on recommending the Seagull based on our own good experience over many years.
First, let me say that Seagull makes good stuff with a good testing and track record. I won’t Seagull bash, except for price and the lack of US certifications. But I actually believe based on their testing that they would pass the ANSI/NSF P231 test. They just have not run it to my knowledge (I asked a few years ago).
There are many options. I have used the Carbontech P231 filters, but I can’t see where to get them at retail. The fit an industry standard housing, but it is a less common one, also hard to find now. The Arogonide P231 is certified as a system, but the housings are very common and you can buy the filters cartridges separately (many brands) through Filters Fast and others. Pentair used to make some good systems, but they seem to have backed out of the market. Surprisingly, there really is very little demand for these relatively expensive filter systems, and there is a reason:
First, remove the major gook with a particle filter (1 micron) when you fill your tank. This will actually remove >95% of the bugs because they are either clumped up or riding on dirt particles. If clean water maters, always prefilter. I like bag filters that can be cleaned and sanitized in the sun, rather than cartriges that can stay wet and grow stuff. Removing particles also means that the chlorine won’t have to penetrate into large particle; the bugs will all be free floating. This also reduces the chlorine demand and reduces the possibility of side reactions with the chlorine. Regular light chorination will handle all of these viruses and bacteria. Carbon is very effective at removing residual chlorine (it is actually sacrificially oxidized by the chlorine). The things that resist chlorine are cysts and parasites, because they are pysically large and tough. A 0.5 micron filter will easily remove those. So by these tree steps (the same ones the city water system uses where there are giardia problems), everything is removed and very fine P231 filtration is not actually needed.
Chlorine gets a bad name, but it is still the standard world wide. What is important is how it is combined with filtration steps. You don’t just dump in a bunch of bleach. That won’t work, won’t be good for you, and won’t taste good.
Drew,
Absolutely great stuff, as always.
We only have a foot pump (standard Whale model). I saw above someone confirmed that a Seagull will work with a foot pump. Do you know if any of the other filters you recommend will work via foot pump, or do they all require pressurized water?
Currently we’re just cruising the Chesapeake, so we pre-filter the marina water, add some bleach regularly, and then use the Whale Aquasource silver-carbon water at the tap for taste (Amazon.com: Aquasource Clear Filter : Sports & Outdoors) although I think it’s overpriced for what it does.
We’re getting ready for more extensive cruising and I’d like to replace that Aquasource with something more effective. However, we need something that will work with foot pump pressure.
Cheers,
Mike
Very interesting topic.
We were drinking WM water straight from the tanks (taste was good) for years, until last refit when we looked inside after 13 years. We’ve found a lot of nasty stuff in the tank corners.
Since then we have small Seagull IV just for drinking water in the galley. Now I can’t imagine drinking water without any filter 😉
So in my opinion even if we have the WM we need a filter for drinking water. Or the tanks need to be cleaned regularly.