Drinking Water from watertanks

[Mike OReilly]

Originally Posted by sailorboy1

BTW since I've a topic posting mood

For those in the cold laying up your tanks/systems with anti freeze in the winter:

There is always going to be "some" left in the tanks after you recommission them. This is the time to be adding some extra bleach. Antifreeze below a certain level becomes bio food.

So… maybe through shear ignorance I’ve been doing the right thing? We definitely use antifreeze in the system. And it is notoriously hard to get it all out in the spring. I wish there was a better answer, but I can’t guarantee I can get all the water out of our system, so antifreeze seems to be the best option.

[a64pilot]

Originally Posted by Exile

I believe chlorine also attacks stainless steel. But like in most things I'm sure, it's probably all about concentration.

I believe chlorine to be similar to UV light, it over time ruins anything, I wouldn’t be surprised to see it eat thru the container it comes in.
It’s I believe an extremely strong oxidizer, and oxidization is of course what happens to “age” stuff, so bleach accelerates the aging process in “stuff”
Now that’s a very generalized statement, made by a confessed layman who really doesn’t know what he is talking about, but I’m bound and determined to keep it out of my water tank, it’s already past the age it was supposed to last, so it’s on borrowed time, and it’s not a matter of if it will fail, only a matter of when.

[dfelsent]

I used to work with xenon chloride and argon fluoride lasers and I learned something about water tank cleaning, indirectly. We had to change the gas in the lasers every so often. The impurities would kill the power output.
What I learned is directly applicable to tank flushing.
Say you have a 101 gallon tank that when you can’t pump any more out there is still 1 gallon left.
If you fill it and empty it you will have 1/99 th of the (chlorine antifreeze whatever) left compared to before. That’s 99 gallons in, 1/100th the concentration.
Instead add 9 gallons. Pump it out. 1/10 the concentration. Again 9 in and pump. 1/10 of 1/10 or 1/100. In less time because you have filled and pumped 18 instead of 99. Repeat twice more and you are at 1/10000 of the original concentration.

Yes this completely ignores stuff on the tank walls but you get the idea. Repeated small dilutions are much more effective than one or two large dilutions.

It really works.
We would do 3 rinses of gas at 1000 to 1 and get an amazingly clean system.

[ben2go]

I use food-grade peroxide to sanitize some of my bottles and containers that I can't get a rag into to clean them.


https://www.amazon.com/diluted-Hydro...language=en_US

[David B]

Originally Posted by tobo

As we get our new Hanse 508 by the end of this year we are thinking of the use of the water tanks for drinking purposes as we are really tired of hauling aboard these masses of PET bottles every week. Reading an article in the German Yacht recently I was impressed by the UV-system "Double Blue" of Instant Trust Marine (InstantTrust Marine - Always clean drinking water on board) . Does anybody have experiences in this field?

We use a Seagull filter. They are used in the aviation industry, and to my knowledge are the only ones certified to provide pathogen free drinking water. Also in a taste test conducted by Practical Boat Owner a few years ago, they came out tops.

[SundayMorning]

Thank you dfelsent.

That is truly useful advice about dilution. Since many of us use chemicals in our tanks and then rinse them clean, that will save lots of time and water.

[admiralslater]

We have plastic vetus tanks on our Outremer, and fill it from both taps and a water maker . When we fill from city water we use a 5 micron filter to keep sediment out of tank . The previous owner had a uv light and an other 5 micron filter befoee the taps. We use the filter but not the light. Our boat sits for a bout 8 months with tanks full to the brim. When we return the water is still good . I do switch it out and clean the tanks abit. Works for us and no water bottles on board . People on charter boats go crazy for bottles of water especially the French

[Cheechako]

Originally Posted by CassidyNZ

We have no municipal water in our home. Have been living off tank water gathered off our roof for 7 or 8 years now. Tastes great, never have any problems. Luckily my local marina collects water exactly the same way, off their roof. They take it one step further with UV irradiation to make it safer. We fill out tanks with marina water. Our boat hasn’t seen chlorine for a decade or more.

With no chlorine in our boat water I know I can do my fresh-water flush of the watermaker without any worries re trashing the membranes.

But despite all that, my wife still carries a dozen plastic bottles of commercial water that cost 5 times what our diesel costs - criminal shame IMHO.

Having a well that supplies limited water I tried roof collection for a while. We have a metal roof. But boy there is a lot of debris, pine needles etc that collect on the roof. Not to mention bird crap. I would never drink that water here. I quit collecting entirely after cleaning the gutters. They are covered with screen, but lots of slime and bugs living inside there. But collection done around the world, I suppose it's a bit different in the Caribe, no pine needles and so much debris.

[CassidyNZ]

Originally Posted by Cheechako

Having a well that supplies limited water I tried roof collection for a while. We have a metal roof. But boy there is a lot of debris, pine needles etc that collect on the roof. Not to mention bird crap. I would never drink that water here. I quit collecting entirely after cleaning the gutters. They are covered with screen, but lots of slime and bugs living inside there. But collection done around the world, I suppose it's a bit different in the Caribe, no pine needles and so much debris.

We haven’t screened our gutters but have a fine screen at the tank inlet. Then we have a heavy filter bag that the water flows through into the tank. Both the screen and the bag are cleaned perhaps every 4 months. When I look down into my tanks which ordinarily are kept in total darkness, the bottom of the tank after 15 years of use, is as clean as the day it was installed.

A TSD test on my tank water shows anywhere between 26ppm and 75ppm depending on temp, season, etc. which is way better than my watermaker will ever achieve. And the water tastes excellent and has never made us sick so I always contest statements about Guardia and all the dozens of other “things” that’ll kill me. I reckon council water with all its chemical treatment is far less healthy than our tank water.

The water we load on the boat at our club/marina is even better being UV screened as well

[GordMay]

Originally Posted by Paul Kelly

How much bleach do you add Mike? It'd be very helpful to know. Thanks.

Hopefully, Peggie Hall may chime in to confirm her recommendations.


1. Prepare a chlorine solution using one gallon of water and 1/2 cup (4
oz) Clorox or Purex household bleach (5-7% sodium Hypochlorine
solution). With tank empty, pour chlorine solution into tank. Use one
gallon of solution for each 5 gallons of tank capacity.

2. Complete filling of tank with fresh water. Open each faucet and drain
cock until air has been released and the entire system is filled. Do
not turn off the pump; it must remain on to keep the system pressurized
and the solution in the lines.

3. Allow to stand for at least three hours, but no longer than 24 hours.

4 Drain through every faucet on the boat (and if you haven't done this
in a while, it's a good idea to remove any diffusion screens from the
faucets, because what's likely to come out will clog them). Fill the
tank again with fresh water only, drain again through every faucet on
the boat.

5. To remove excess chlorine taste or odor which might remain, prepare a
solution of one quart white vinegar to five gallons water and allow this
solution to agitate in tank for several days by vehicle motion.

6. Drain tank again through every faucet, and flush the lines again by
fill the tank 1/4-1/2 full and again flushing with potable water.

[herbhunt]

Like many of you we drink solely out of the tank and find the prevalence of the use of 'disposable' plastic water bottles by sailors to be very bad for the environment. Even when carefully deposited on an islands 'recycling' facility they often end up back in the ocean or 'burnt'.

So our approach is:
1- Be careful with sources and always filter the water on the way into the boat. Particulate filter not charcoal as we dont want to take the chlorine out of treated water on the way in.

2 - Don't put antifreeze in the water tanks. We empty them and leave the drain cocks open in the winter so we dont have the problem of trying to get the residual anitfreeze out of the tanks.

3 - Occasionally dose with small amounts of chlorine especially if we are operating solely off water maker water.

4 - Use a carbon/particulate filter on the drinking water tap. Yes they can have growth in them if left a long time so we dry them out if we are leaving the boat for a while.

[Arsydian]

Dont ask me, I still drink from the garden hose..

[DHLyman]

Clean the water tanks with water and Clorox bleach. Then empty and refill.
No sense in filtering all the water in your tanks, only that which you drink, so buy a Brita water pitcher that filters the water when you fill it.
We used that system for three years living aboard. While in the tropics most of the water use was for rinsing off the kids after swimming.

[wb.andrews]

I discovered Purogene this season. More expensive than bleach, but no odor or taste. Used in airplane water tanks. Long lasting.

[kelbylinn]

We use Aqua Mira treatments in our two 75 gallon tanks. They treat 60 gallons of water for long term storage. Never a problem with odors, taste, or anything after 10 years or so. Amazon and others have it available.

https://www.amazon.com/Aquamira-Chlo...0&psc=1http://