Water tanks...

[lefkasman]

I understand that to avoid horrible things such as Legionellas, Cholera, Typhoid and other such things growing in the boats water tanks it is necessary to treat the water with some sort of purifying tablet.
Now we don't drink the water from our tanks, just use it for washing, bottled water is used for drinking, however to be on the safe side I have been using Aqua Clean Tabs but at 15 Euroes for thirty two tablets and thats only enough enough to treat 800 Lt's its an expensive business.
So question is what do you guys use? is there anything cheaper? remember we don't drink it, or is it essential to treat it at all?
Any suggestions apreciated, thank you.

 

[saltwater_gypsy]

I've drunk lots of Greek water to no ill effect! but.... water kept for a long time in the tank is a different story... wouldn't drink that unless I was really sure about its history.
I think that you only have to sterilize your tank periodically to keep the bugs in check.
I suggest that you keep half-a dozen bottles of tap water on board and replenish as required.

 

[Evenspread]

Can't think why you should want to spend money on cleaning water you are not going to drink. Do you treat your domestic hot water (which generally comes via a storage tank) before you wash?

 

[2nd_apprentice]

Bleach

 

[SailBobSquarePants]

Bad water...

I've done a lot of work in Mexico and South America, and I can tell you from experience that bad water can infect you even if used for brushing teeth, or washing greens for salads. If the water is bad, and it isn't boiled or treated, even trace amounts can convey an infection. I've twice had water-born illness over there...once just from a single ice cube that went into a drink. Most repeat visitors learn to brush teeth with bottled water very quickly, avoid salads, and even ice cubes.

The good news is that the water that most of us fill our tanks with is clean enough to start...but left untreated, water in a holding tank becomes a breeding ground for what few infections can get a toehold. And the side walls of tanks are easily covered in what is called "bioslime", which is an organic thin film of contaminants that does not wash away easily, particularly in older tanks.

Having said that, we drink glasses of water from our 44-year old fiberglass tanks on my Nicholson 32. But each season, I HEAVILY disinfect the tanks, using a large access hatch to drain and scrub repeatedly the inside of the tanks with a long-handled lambswool mop, some dish soap, and lots of water to rinse. Then (as I read here on YBW) I further disinfect the tanks with a double strength solution of Milton's sterilising fluid (http://www.boots.com/en/Milton-Sterilising-Tablets_25422/), which I let stand for 24 hours while circulating in the tank via a 12v submersible pump to keep it agitated). Another rinse follows, and then the tanks are good to go.

I do then treat every tank with Aquapure tablets, just in case.

Others may not go to such lengths, but when I first did this I was shocked at how much "gunk" came off the sides of the tanks when I started scrubbing, and indeed they changed colour from a yellow to white/grey. That was all stuff that was growing there, acting as a medium for bacteria and viruses. The lambswool head was not cheap, but did an incredible job of scrubbing the tank, compared to two different brushes I had tried (and also didn't scratch the fiberglass).

You may not have such a good access hatch, or not have tanks that are so old. You may be fine with just a good rinse with double strength Milton's and Aquapure tablets.

BTW - I believe Aquapure are expensive because they have less of a taste than other water purification tablets. You can buy just plain iodine tablets from camping and outdoorsmen's stores, which are probably cheaper but do leave more of a taste I believe. If you are just brushing your teeth and using it for washing up that might be a cheaper route.

 

[Ubergeekian]

So question is what do you guys use?

Dose with puriclean, four flushes and refill at the start of each season. Nothing after that.

 

[dmmbruce]

Dose with puriclean, four flushes and refill at the start of each season. Nothing after that.

Ok, good. But how do you flush out a tank?

I have two 20 gal flexible tanks, each has a small hand pump/tap at each sink. It takes 'for ever' to pump out even half a tank full of water.

At the start of a season, I pump out what is left from last year, it is sometimes a bit brown! Then refill. (If it had been brown, I put a bit in, then pump, then a bit more etc until it is clear.) After refilling, I put in Puritabs, leave for 24 hours, and all is well again. Flushing four times sounds great, but how?

This is of course in the UK. When in the tropics it was entirely different and I completely agree with the post above. Ice cubes were famous for trouble, and salads etc.

Mike

 

[claudio]

We use bleach, sold as 'non perfumed' suitable for washing vegetables and fruit. Easier to obtain and lots cheaper than Milton (same stuff anyway). Dosage we use is 10ml per 100L seems to work well, no problems, currently in Canaries, ambient temp here is around 30 deg C at the moment.

 

[Chris_Robb]

We use bleach, sold as 'non perfumed' suitable for washing vegetables and fruit. Easier to obtain and lots cheaper than Milton (same stuff anyway). Dosage we use is 10ml per 100L seems to work well, no problems, currently in Canaries, ambient temp here is around 30 deg C at the moment.

I do the same. I really don't think in warm climates you can leave a tank untreated even if you never drink from it.

 

[PeterGibbs]

I understand that to avoid horrible things such as Legionellas, Cholera, Typhoid and other such things growing in the boats water tanks it is necessary to treat the water with some sort of purifying tablet.
Now we don't drink the water from our tanks, just use it for washing, bottled water is used for drinking, however to be on the safe side I have been using Aqua Clean Tabs but at 15 Euroes for thirty two tablets and thats only enough enough to treat 800 Lt's its an expensive business.
So question is what do you guys use? is there anything cheaper? remember we don't drink it, or is it essential to treat it at all?
Any suggestions apreciated, thank you.

Before closing down for the winter, drain all water and flush out with Milton / PL equivalent. Leave some in the tank over winter.

Spring - check condition of tank if you can visually, and re-Milton it overnight. Drain out and refill.

Keep the water on the move during the season and be scrupulous about the quality of new water added to the tank. No reason why you should not use this for everything. I have a Whale cold water filter inserted in the galley tap for taint free drinking / tea making etc. - replacing the cartridge every spring, it's good the the whole summer.

This procedure works every time for me - no need for bottled water at all. The risks you quote are almost unheard of in practice - if normal care is taken. What occurs most often in boat tanks is a build up of green weedlike growth - not harmful but best avoided. If you contract typhoid or cholera in your tank your vessel will be quarrantened, you will spend time in hospital and you will need something more than a tablet to cleanse it! Legionella is an airborn bacterium anyway....

PWG

 

[lefkasman]

Hey thanks guys... specially Bobsquarepants (what a user name! got to be a story there) for going into such detail, and Claudio n Chris Robb (you two seem to appreciate the problem of the heat aspect its been a real problem this August here in the Ionian).

Anyway you have all confirmed my suspicions that bleach is a good substitute, thanks for all of your inputs, the response on this forum never fails to amaze me.

 

[sds]

water tank

Vinegar !

Its cheap (get it by the gallon from garden centre's - used to clean and disinfect grenhouses as the end of the season)

Environmentally freindly and really works.

If any is left over after flushing at least you know its not bleach or chemicals.

 

[Bosun Higgs]

going back top my working days, I even had to have the irrigation system for the works social club bowling green treated against legionella because it is spread by aerosol drops. In other words splashes from a running tap.

It is a nasty infection so I wouldnt begrudge the small amount of dosh you mention to be on the safe side.

 

[SailBobSquarePants]

Anyway you have all confirmed my suspicions that bleach is a good substitute, thanks for all of your inputs, the response on this forum never fails to amaze me.

Umm, I am not sure if things are that clear. In your initial post, you said you were using AquaPure and so many tablets _treated so much water_.

I think bleach may be used as a substitute for CLEANING the tanks and having them flushed afterwards, but not for treating the water being held in them. Bleach is, after all, a poison.

If you are just talking about treating the water being held in the tanks (stabilizing it, preserving it, whatever), then you are still reliant upon AquaPure, or iodine, or luck.

And totally agree with the above poster about the Whale water filters - I have one fitted on each of my cold taps (well, on my boat that is EVERY tap, lol), and they do catch a number of bacteria and viruses. The carbon filters also help filter out the taste of any preservatives.

How good does it taste? Well, I use mine to add to the scotch even...

 

[nedmin]

In 30 yrs of boating I have only once used purifying tablets,it made the tea taste terrible.I try to end a boating session with a minimum of water.Then before next session I drain off all the water,refill with water pump on and tap open for 2 or 3 minutes,I then turn pump off and fill tank.There is enough chlorine in the water to kill bacteria.We clean our teeth with it,taking care not to swallow.We boil for tea,coffee but do not drink it out of tap,but use bottled water.We have never had any problems.

 

[claudio]

I think bleach may be used as a substitute for CLEANING the tanks and having them flushed afterwards, but not for treating the water being held in them. Bleach is, after all, a poison...

In large doses, or neat bleach, is a poison, so is table salt. The bleach suggested is used for washing fruit and vegetables, not the Domestos type toilet cleaners!

Milton can be used for water treatment, bleach is used in UK waterworks to chlorinate the water supply.

See link http://en.wikipedia.org/wiki/Sodium_hypochlorite

 

[lefkasman]

Thanks again Claudio....seems the answer was there in good old Wiki all the time....

Water treatment

For shock chlorination of wells or water systems, a 3% solution of household bleach is used. For larger systems, sodium hypochlorite is more practical because lower rates can be used. The alkalinity of the sodium hypochlorite solution also causes the precipitation of minerals such as calcium carbonate, so that the shock chlorination is often accompanied by a clogging effect. The precipitate also preserves bacteria, making this practice somewhat less effective.

Sodium hypochlorite has been used for the disinfection of drinking water. A concentration equivalent to about 1 liter of household bleach per 4000 liters of water is used. The exact amount required depends on the water chemistry, temperature, contact time, and presence or absence of sediment. In large-scale applications, residual chlorine is measured to titrate the proper dosing rate. For emergency disinfection, the United States Environmental Protection Agency recommends the use of 2 drops of 5%ac household bleach per litre of water. If the treated water doesn't smell of bleach, 2 more drops are to be added.

The use of chlorine-based disinfectants in domestic water, although widespread, has led to some controversy due to the formation of small quantities of harmful byproducts such as chloroform.

An alkaline solution (pH 11.0) of sodium hypochlorite is used to treat dilute (< 1 g/L) cyanide wastewater, e.g. rinsewater from an electroplating shop. In batch treatment operations, sodium hypochlorite has been used to treat more concentrated cyanide wastes, such as silver cyanide plating solutions. A well-mixed solution is fully treated when an excess of chlorine is detected.

 

[snowleopard]

Bleach

Agreed. You have to make sure you get plain bleach, not 'thick' stuff and don't put too much in. People who use watermakers are advised to add bleach to prevent algae growing. We once put too much in (an eggcup in 50 gals) and it tasted like a swimming pool!