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khughes
Samba Member
Joined: July 13, 2013
Posts: 888
Location: Phoenix AZ
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 Posted: Tue Oct 06, 2020 4:24 pm Post subject: Re: UV-C Water Tank Sterilizer |
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| Corwyn wrote: |
| Somebody had to get this conversation started. . . .😎 |
Hey, it's a nice idea, and won't hurt anything. Just gotta use it as a belt and suspenders approach, not as a primary control for water quality. After 40 years in pharma developing and validating pretty much all forms of sterilization technology as well as high purity water systems...I'm a bit cautious of claims. 
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'86 Westy FAS GenV Turbo (Marvin) |
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OldSpice
Samba Member
Joined: June 10, 2015
Posts: 178
Location: 87 syncro westfalia Subaru ez30
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| Posted: Tue Oct 06, 2020 5:05 pm Post subject: Re: UV-C Water Tank Sterilizer |
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| kourt wrote: |
The better way to do UV purification in the RV setting is to build an inline UV filter into the supply line from the tank to the sink. You set it to power on only when the pump is running.
There are a lot of good products that already do this. This site has a few, including a legitimate in-tank UV sanitizer.
https://ultraviolet.com/uv-water-purification/
I agree with the other poster who mentioned that UV light will degrade the plastic tank. It's better to build something into the sink supply line.
I thought of doing a project like this, but for now I'm just using a separate Pentek filter system that is switchable. Turn it off for washing dishes, turn it on for filling water bottles. This is very popular with my guests, and works well as long as you manage it properly. Photo below.
kourt
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would love to see pics of how you plumbed/mounted it |
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WiboBusMan
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Joined: September 26, 2009
Posts: 167
Location: Canada
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| Posted: Tue Jul 22, 2025 7:05 pm Post subject: Re: UV-C Water Tank Sterilizer |
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I'm reviving this old thread seeking an update from others and to provide a reference to current readily available UVC units on eBay.
I would welcome any updates from OPs as to their experience over the last 5 years - were there any tank "infections" or did this provide a lasting solution?
Long story short, I had a decades long run of good fresh water from the tank, without any chemical treatment, until about a year ago. I had been fairly careful in not letting the water sit in the tank after a camping outing, and the decent quality municipal water from my home probably had just enough chlorine in it to keep any nasty organisms at bay.
Whether it was bacteria, mold, yeast or algae, I don't know, but suddenly the taste was off, and awful. A dump, a chlorine shock, a bit of a scrub and a good rinse and all was good again. I got to thinking that there must be a way to harness excess solar power to sanitize my water supply with my solar panels and LiFePo4 battery setup.
I use the Electrodacus system that has an automatic diversion of solar panel power to a secondary circuit whenever the batteries are topped up. These have a pretty low current draw, so a good battery setup could probably handle it without issue.
I found the item illustrated on eBay - "270-280NM UVC Lamp DC12-24V LED Disinfection Light Water Purifier Lamp". There are multiple vendors.
Installation was pretty straightforward, drilled holes with a ½ inch bit, which fit perfectly. The fit was tight to the point that a little force was used to pop the unit in and was secured with two small brass ¾ inch wood screws. No leaks at all.
The tank is full of water in the photo. The camera picks up the UV light a lot more than your eyes - where you see only a faint violet glow:
From inside the cabinet (on the outside of the tank):
W
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Science has sacrificed Truth on the altar of its narrative. |
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DanHoug
Samba Member
Joined: December 05, 2016
Posts: 5722
Location: Bemidji, MN
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| Posted: Tue Jul 22, 2025 8:00 pm Post subject: Re: UV-C Water Tank Sterilizer |
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$5.99 eh? despite the claims of 3 log reduction in the ad text, my question to you is... is that clear sphere over the LED UVC emitter acrylic or quartz glass? because acrylic blocks UVC while quartz glass allows UVC to pass.
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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WiboBusMan
Samba Member
Joined: September 26, 2009
Posts: 167
Location: Canada
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| Posted: Wed Jul 23, 2025 3:50 am Post subject: Re: UV-C Water Tank Sterilizer |
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They claim it is quartz, and it certainly did not feel like plastic...
W
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DanHoug
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Joined: December 05, 2016
Posts: 5722
Location: Bemidji, MN
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| Posted: Wed Jul 23, 2025 8:38 am Post subject: Re: UV-C Water Tank Sterilizer |
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| WiboBusMan wrote: |
They claim it is quartz, and it certainly did not feel like plastic...
W |
okay, that's good. UV disinfection is kinda cool in this application but i question the usefulness. mind you, for $6 and low current draw, there is no downside.
the LED has a beam angle of 120 degrees. while it will eventually zap much of the free-floating bacteria in the water tank but unlike a dispersed disinfectant does nothing for the tank materials that the beam does not reach. so. the 'shadow areas' of the beam will continue to grow bacteria as will the tubing, pump, faucet, etc. and to be honest, a 3 log removal, 99.9% is not very much in the water quality world.
i say all this not to poo-poo the installation but just to caution that it is not a panacea. i would not trust it make unsafe water potable, you still need to rely on fill ups of quality water. it will do nothing to control slime growth in areas the light doesn't reach, only a dispersed disinfectant will do that. a little dash of hydrogen peroxide in the tank will accomplish that. you want to shoot for 25ppm hydrogen peroxide which equates to about 2 TEASPOONS of 3% peroxide per gallon of water. or 1/2 cup per full 12 gallon Westy water tank. i would be comfortable cutting that in half, a 1/4 cup per tank, when you are filling with known good water like from your own tap. this keeps the water fresh for the entire fill, disinfects the tank and plumbing, and would actually kill pathogenic organisms (at 25ppm) from unsafe water.
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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vanis13
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Joined: August 15, 2010
Posts: 4434
Location: ABQ NM USA.... Except when not
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| Posted: Wed Jul 23, 2025 8:53 am Post subject: Re: UV-C Water Tank Sterilizer |
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| DanHoug wrote: |
| WiboBusMan wrote: |
They claim it is quartz, and it certainly did not feel like plastic...
W |
okay, that's good. UV disinfection is kinda cool in this application but i question the usefulness. mind you, for $6 and low current draw, there is no downside.
the LED has a beam angle of 120 degrees. while it will eventually zap much of the free-floating bacteria in the water tank but unlike a dispersed disinfectant does nothing for the tank materials that the beam does not reach. so. the 'shadow areas' of the beam will continue to grow bacteria as will the tubing, pump, faucet, etc. and to be honest, a 3 log removal, 99.9% is not very much in the water quality world.
i say all this not to poo-poo the installation but just to caution that it is not a panacea. i would not trust it make unsafe water potable, you still need to rely on fill ups of quality water. it will do nothing to control slime growth in areas the light doesn't reach, only a dispersed disinfectant will do that. a little dash of hydrogen peroxide in the tank will accomplish that. you want to shoot for 25ppm hydrogen peroxide which equates to about 2 TEASPOONS of 3% peroxide per gallon of water. or 1/2 cup per full 12 gallon Westy water tank. i would be comfortable cutting that in half, a 1/4 cup per tank, when you are filling with known good water like from your own tap. this keeps the water fresh for the entire fill, disinfects the tank and plumbing, and would actually kill pathogenic organisms (at 25ppm) from unsafe water. |
Very helpful for those of us not familiar in this area. Thanks for sharing.
so the 1/4 cup 3% peroxide could be this? - https://www.walgreens.com/store/c/walgreens-3-hydrogen-peroxide/ID=prod6373232-product
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83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace
www.SuperVanagon.com - some stuff I make |
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DanHoug
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Joined: December 05, 2016
Posts: 5722
Location: Bemidji, MN
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| Posted: Wed Jul 23, 2025 9:37 am Post subject: Re: UV-C Water Tank Sterilizer |
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that's fine. any brand that is 3%. don't buy "food grade" as that is 30% and can cause nasty burns.
mind you, one needs to 'shock treat' the tank and plumbing periodically with a quart of bleach in a full tank of water. scrub the tank interior with a blue dish scrubbie too. turn on the pump until you smell bleach then let the system sit for an hour and dump it out. rinse the tank with clean water as well as the plumbing. if you haven't done this for a while, you'll notice your clear water lines are black with slime. the bleach treatment will turn the slime translucent but may not totally remove it. that's fine, it's dead and will get cleaner over time with periodic shock treatments and a resident dose of peroxide.
i do the bleach thing once at the beginning of camping season per year. when i fill with water from home, i don't add any peroxide.
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-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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WiboBusMan
Samba Member
Joined: September 26, 2009
Posts: 167
Location: Canada
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| Posted: Wed Jul 23, 2025 4:52 pm Post subject: Re: UV-C Water Tank Sterilizer |
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Thanks for the feedback and helpful suggestions for healthy camping!
W
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khughes
Samba Member
Joined: July 13, 2013
Posts: 888
Location: Phoenix AZ
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| Posted: Wed Jul 23, 2025 7:13 pm Post subject: Re: UV-C Water Tank Sterilizer |
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[quote="DanHoug"]
| vanis13 wrote: |
that's fine. any brand that is 3%. don't buy "food grade" as that is 30% and can cause nasty burns. |
While 30% peroxide is not commonplace, or readily available in retail settings, this is an important safety point to keep in mind when using H2O2 or any strong oxidizer. Had a client once that was disinfecting a huge water pretreatment system to feed a water for injection skid. The protocol was to use 5% peroxide injected at the start of the loop and continue injection until >3% was measured at the end of the loop. Bright engineer decided it would be quicker to just use 30% until reaching >3% at the end. This was an overhead routed PVC system. Needless to say, the first half of the loop melted and fell in the floor before any peroxide got to the other end. Kind of like adding water to concentrated acid. Great hand warmer.
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