Cleaning water from tank

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pcatterall

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Our Neptunian has a good sized water tank (100gallons) The water in Spain is often 'suspect' before it goes into the tank. The tank is grp and can be cleaned, when taking on good water we were happy to use a chemical purifier and then a fine filter. We are less happy with this system and 'Spanish water' I understand that there are domestic systems on the market that use ultra violet light etc to purify drinking water. It would be nice to avoid having to carry so much bottled water. Any experience or knowledge on offer please?
 
UV sterilisation is fine for water you will use immediately, but it doesn't stop bugs from multiplying after the water has been sterilised. There's no continuing effect as there is with chlorine or oxygen based systems.

It isn't a DIY thing; UV at the intensity and wavelengths required for sterlisation is dangerous; it can blind you very quickly.

I understand there are "black box" systems available, but I don't know whether 12volt systems are available. It is power hungry.

My late wife did research into ways to improve its efficiency, but none were close to being commercially viable.
 
It is sometimes difficult to reliably know if the water is OK or not, the locals at Burriana say they wont drink the tap water but is that just because it is a little brackish or chlorine tasting? Even in UK some younger people are surprised that I drink water from the tap!! they have become convinced that only bottled water is OK. It is an issue when our 'crew' hear that the water "is not good" they are turned off and blame their 'gyppy tummy's'
on the water not the several bottles of sangria they consumed!! perhaps I just need a device that simply looks effective ?
 
All domestic water supplies have bugs in them; they are kept below certain limits specified by regulations by the water companies, but they are still there. The point is a) that they are present at low levels and b) we've been exposed to them all our lives, so we have good immunity to them.

If water is stored in a tank, it is likely that the bug count will rise unless there is a persistent sterlising agent such as chlorine present.

If we go to another country, point a) still holds, but the bugs may well not be the ones our body has immunity to. I heard this put very well by the manager of a hotel in Hong Kong! On being asked by an American whether the water was safe to drink, he said "I've been drinking it all my life, and it does me no harm. But I'm used to it. You might not find it so good because you aren't used to it". In fact my late wife and her family generally only drink boiled water; that's pretty common in Hong Kong because although the quality of the water going into the pipes is fine, the higher temperatures mean that bugs can multiply more rapidly than in colder climates, so if you're on the end of a long pipeline, the bug count at the tap might be higher than at the processing plant. Of course, pretty much all potable water is at least slightly chlorinated to reduce contamination effects.
 
In Hong Kong many people put filters on their cold water tap in the kitchen for drinking. But I’ve been using unfiltered tap water here for the ice in my G&T for years with no ill effects. Could be that the amount of gin that I use kills any bugs in it.
 
We dose tanks with chlorine-based sterilizer liquid or tablets after every refill and remove the taste with a carbon filter at the tap.
 
Think about how potable water is treated (this may be new to you). Rough filter, chlorinate, fine filter for cysts. Not hard to do on board and make fine tasting water, but you have to follow the steps. I've built industrial and municipal systems and written on boat systems. This is the short version. Don't skips steps, and don't substitute other filter types unless you really know your filters.

Water treatment. The short version.

It is possible, of course, that you still won't like the taste. But it will be safe.
 
AntarcticPilot said:
All domestic water supplies have bugs in them; they are kept below certain limits specified by regulations by the water companies, but they are still there. The point is a) that they are present at low levels and b) we've been exposed to them all our lives, so we have good immunity to them.

If water is stored in a tank, it is likely that the bug count will rise unless there is a persistent sterlising agent such as chlorine present.

If we go to another country, point a) still holds, but the bugs may well not be the ones our body has immunity to. I heard this put very well by the manager of a hotel in Hong Kong! On being asked by an American whether the water was safe to drink, he said "I've been drinking it all my life, and it does me no harm. But I'm used to it. You might not find it so good because you aren't used to it". In fact my late wife and her family generally only drink boiled water; that's pretty common in Hong Kong because although the quality of the water going into the pipes is fine, the higher temperatures mean that bugs can multiply more rapidly than in colder climates, so if you're on the end of a long pipeline, the bug count at the tap might be higher than at the processing plant. Of course, pretty much all potable water is at least slightly chlorinated to reduce contamination effects.
Click to expand...
We only use water made by our RO system when cruising. We have UV treatment to the RO water before it enters our tank. UV treatment is very simple and economic. It works well with RO water as the particulate level is very low. The bugs have nowhere to hide so get a nice zap from the UV.
We are about to enter a marina in Portugal where we will be using local water. Slightly sceptical about having mains water in our super clean tank
 
Thanks all, interesting stuff! I would like to find some sort of hose attachment to prefilter the marina water as we fill the tank ( I can find plenty for motorhomes, they have those 'special connectors' but I guess I could just cut them off? We will then use our water treatment chemical as normal and get a new filter for our Whale filter. I will then have to self test all this to wean the crew off bottled water!!
Thanks again.
PS perhaps geem could tell us more about his 'Ulterior Violent' treatment?
 
Skellum said:
In Hong Kong many people put filters on their cold water tap in the kitchen for drinking. But I’ve been using unfiltered tap water here for the ice in my G&T for years with no ill effects. Could be that the amount of gin that I use kills any bugs in it.
Click to expand...
Yes, at least two of my sisters-in-law have such filters. But they still boil water before drinking it! And a routine appliance in most Hong Kong apartments is a water boiler (e.g. 1634294860679.png
 
AntarcticPilot said:
Yes, at least two of my sisters-in-law have such filters. But they still boil water before drinking it! And a routine appliance in most Hong Kong apartments is a water boiler (e.g. View attachment 124159
Click to expand...
Boiling seems to be the ultimate solution! but do fuel issues and space/time for cooling not limit its use on a boat? Our large tank is, in some ways a liability. If we fill up then leave the boat for long periods in summer then, bacteria can multiply like mad. We are trying to just part fill when in the marina and only fill the tanks when we are going to use the contents quickly.
 
To keep the water fresh when travelling across the paries all those years ago the the wild west , they used to put a silver dollar in the water buts. You can buy high quality silver wire used for jewellery making. I coiled a whole load and dripped it insto the water tank. I also pulled it through the pipework when I replaced it a couple of years ago. It works well and I have had no bug issue. Using silver gives you ongoing protection.
 
tross said:
To keep the water fresh when travelling across the paries all those years ago the the wild west , they used to put a silver dollar in the water buts. You can buy high quality silver wire used for jewellery making. I coiled a whole load and dripped it insto the water tank. I also pulled it through the pipework when I replaced it a couple of years ago. It works well and I have had no bug issue. Using silver gives you ongoing protection.
Click to expand...
The theory behind this is perfectly sound, but ensuring sufficient contact between the silver and the water is the tricky bit; silver nanoparticles on carbon are extremely effective - the carbon adsorbs bugs with its high surface area, and the silver kills them. I can imagine silver wire being effective, but the silver dollar wouldn't have a great enough surface area to be very effective.
Incidentally, jewelry silver isn't particularly pure (see Silver standards - Wikipedia) - like gold, it's alloyed with a small proportion of other metals to make it stronger. The silver wire used for high performance electrical work is much purer (pure silver has a higher conductivity than copper). However, it's entirely possible that electrochemical reactions in slightly impure silver might release silver ions into solution, increasing the effectiveness.
 
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pcatterall said:
It is sometimes difficult to reliably know if the water is OK or not, the locals at Burriana say they wont drink the tap water but is that just because it is a little brackish or chlorine tasting? Even in UK some younger people are surprised that I drink water from the tap!! they have become convinced that only bottled water is OK. It is an issue when our 'crew' hear that the water "is not good" they are turned off and blame their 'gyppy tummy's'
on the water not the several bottles of sangria they consumed!! perhaps I just need a device that simply looks effective ?
Click to expand...
Slight digression: sangria should not come in bottles, it should be freshly made by your barman! (sorry, bartender :( )
Perhaps we should do what they did in the Middle Ages; forget the water and drink beer instead :)
 
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