Commissioning the fresh water system

Piers

Piers

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Guernsey, Channel Islands
www.playdeau.com
After months of not being able to use or visit Play d'eau, we will need to commission the fresh water system. In itself, not a problem (Milton Fluid rules OK), but I'm wondering about adding a UV light for sterilising the water when it leaves the tanks. All we have at the moment is a 2 micron carbon filter.

Is a UV light a good idea?
 
Buildings using water for adiabatic cooling sprays for their AC system condensers and dry air coolers routinely use UV lights to kill bugs, indeed it might be a legal requirement to prevent legionella build up.

In the UK risk of legionella on boats is lower, but I routinely hang the shower head out of the head window and let it run for a minute or so on maximum heat to purge the head of any nasties. Showers produce the fine mist that is where legionella bacteria is most likely to be breathed in.

Not sure where a 12v UV water lamp would be available from though.
 
Be aware the bulbs go off with time .This is different to actually going out .As they rack up hrs the UV quality can diminish to a basically useless level .I remember there’s a spectrometer thingy to test ......and thus trigger replacement.

I would go for a submersible so it’s on all the time you have 220/240;v .
You will need easy access to the top of the tank to pull it for testing now and again .
Flow ones might restrict an already pressured supply to the point you and occupants may regret .You won,t know ( despite the blurb on the box about GPH ?) until after it’s actually fitted and that nice shower is reduced to a pathetic dribble .These ought to be spectrometer tested as well btw so the same potential access issues .

For me I just always use a proprietary water disinfectant for boats + RV at every fill up , 500 L and up the last dose before winter ,
Well you know the chemical is gonna get everything into every nook and cranny .

How ever in desperation a 2 % bleach etc sol soaked and flushed would work as a shock clean .

Submersible UV Systems: UV Lights for Water Tanks from EMWC
 
You can readily buy inline UV light systems for aquariums (220volts). I've had a few when I had breeding tanks. Although I would say that the same body of water is passing through it several times in a day. I would be rather surprised if UV light unless of exceptional strength would really kill very much on a single pass.
 
Personally, like you I would do an initial shock dose with Miltons, flush and then periodically add in small quantities.
 
My 70ltr Tank gets a good dose of Sterilising tablets and pump through system ...
Milton is fine for a clean system ... but I go for the stronger ex Military tablets ... the fumes inside the tank also kill off anything that lingers on the tank walls above the water.
Yes - my tank water takes a couple of flushes to reduce the chlorine tint ... but I'd rather that than some bug get me !!

To be honest - my FW tank only really gets used seriously once or twice per year ... rest of the time its just for washing hands etc.

The tablets I use are Army Surplus Oasis Tablets .... spec'd 1 tab for 20ltrs water. But I up that to 1 tab per 10ltrs .... My thought is - if its good enough for army to be able to drink river / lake water - then I reckon its good enough for me !!
I bought a box of 1000 tabs !! My house was on well water till a couple of years ago - so I used to dose the well once a week. I still have part of the box left over ...
 
thejonesey said:
How does it work with Milton? Put in 500ml fill and then empty tank? We have never bothered but given she has sat for 10weeks...
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I can only say what works for me. From empty tanks I remove any gauze and filters. Flush the tanks for a half hour or more filling water while opening all taps. Close off taps and add Milton's to the required dose. Leave for 24 hours. Empty tanks and flush again for half an hour with fresh water. Fill tanks and then add a Milton cubes at a ratio of about 1/10th dose each fill up (You cant taste it). Never keep water in the tanks for longer than two weeks without a full recycle of fresh water.

Side note. If you have a healthy black water (fresh water) system do not flush the toilet when you have Miltons at full dose. Most black water systems start smelling and giving problems when you kill off the healthy bacteria in them.
 
We used UV treatment for the water supply to our holiday letting cottages, along with all the other filtration equipment . UV is required to kill the bugs and, as other have said, the bulbs "go" over time. Our replacement regime was annually at the start of the season. I'd have thought that a 12v UV system on a boat would be an excellent idea and possibly better adding chemicals that can taste - something like this?? 12 Volt Ultra Violet Water Sterilisation Systems
 
I would say a dose of Milton and a good flush would do the job.
We use the boat all year and try not to carry to much water around all the time, so it is refreshed on a regular basis. water is used in the same way as at home with no issues apart from swmbo not keen on cups of tea because it tastes “ odd” , coffee ok though. Does anyone think a carbon filter under the sink would help ?.
 
robmchugh said:
We used UV treatment for the water supply to our holiday letting cottages, along with all the other filtration equipment . UV is required to kill the bugs and, as other have said, the bulbs "go" over time. Our replacement regime was annually at the start of the season. I'd have thought that a 12v UV system on a boat would be an excellent idea and possibly better adding chemicals that can taste - something like this?? 12 Volt Ultra Violet Water Sterilisation Systems
Click to expand...

I think the giveaway is in the description. Constant 12v. i.e. these sit and recycle water in numerous passes. OK for a tank bit maybe not for water on demand.............?? can you confirm
 
Portofino said:
Be aware the bulbs go off with time .This is different to actually going out .As they rack up hrs the UV quality can diminish to a basically useless level .I remember there’s a spectrometer thingy to test ......and thus trigger replacement.

I would go for a submersible so it’s on all the time you have 220/240;v .
You will need easy access to the top of the tank to pull it for testing now and again .
Flow ones might restrict an already pressured supply to the point you and occupants may regret .You won,t know ( despite the blurb on the box about GPH ?) until after it’s actually fitted and that nice shower is reduced to a pathetic dribble .These ought to be spectrometer tested as well btw so the same potential access issues .

For me I just always use a proprietary water disinfectant for boats + RV at every fill up , 500 L and up the last dose before winter ,
Well you know the chemical is gonna get everything into every nook and cranny .

How ever in desperation a 2 % bleach etc sol soaked and flushed would work as a shock clean .

Submersible UV Systems: UV Lights for Water Tanks from EMWC
Click to expand...

Play d'eau has four separate water tanks, manifolded as required. Hence, I'd need 4 submersibles. An inline would be more practical provided it can cope with the flow. I'll start searching.
 
We shower, wash up and flush the loo with what's in the tanks but we never ever drink from them. Each trip, fill up numerous two litre bottles from the cold main before setting off. So far so good.
 
Catalina36 said:
We shower, wash up and flush the loo with what's in the tanks but we never ever drink from them. Each trip, fill up numerous two litre bottles from the cold main before setting off. So far so good.
Click to expand...
We've always drunk water from Play d'eau's water tanks. Apart from regularly sterilising the tanks and renewing the carbon filter, we haven't had an issue in 17 years. But with non-use for so long, I'm thinking of the UV light.
 
We have a garden pond of about 700 gallons capacity with a pump which circulates it about once an hour. It has a 240 volt UV lamp in the pipe so that all the water goes through it 24 times a day. It's supposed to keep the water clear but at this time of the year the algae bloom overcomes it for a few weeks. The chances of a 12 volt UV killing all germs in water which might have been stored for weeks, in a single pass when the water is drawn off is zero. If it were that easy the water company would use that method instead of chlorine.
 
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