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Could one use an aquarium style UV lamp to keep a greywater storage tank free from harmful organisms? Answered



Best Answer 8 years ago

As long as your light is putting out UV-C light it will work. The question is how effective will it be.

There are two ways that you can go about this. One, mount the light in the tank and hope that the water coming into the tank will stir it enough to churn up any baddies living at the bottom. 

Two, mount the light in a smaller chamber that the grey water goes through before the tank. The water flows through the chamber and gets sterilized before getting to the tank. The smaller sterilization chamber would ideally be designed to make the grey water pass under the light in a thin curtain to maximize light exposure.

The disadvantage of approach two is if the tank has micro baddies then they would be free to propagate there. If you use some bleach in the tank when first setting it up it should be good. If you don't like bleach, try hydrogen peroxide that they sell for gardening. They sell it to oxygenate soil so it won't harm plants.


7 years ago

Thanks for all your answers!
I happened to work with soemone who built their own house, complete with cistern.
This isnt what he uses, but he pointed toward the right direction:




From these sites, I have concluded that it could be done, but a purpose built device would be worth the price.
In order to keep the costs low, a 1 or 2 GPM UV device could circulate the water,
Sediment filtering would be necessary,
I originally wanted to just flush my toilet with gray water, but it would seem that a little chlorine would work better and cheaper for that.
I see UV sterilization as being a good fit for using grew water in the garden, on edible plants.

. Yes, there are aquarium UV sterilizers that should work very well if properly sized. Same technology as used in municipal water supplies, just on a much small scale.

You CAN use UV sterlisation, but it relies on much harder UV than an aquarium light. UV penetration is very limited in water, and to get the energy density you need, you HAVE to have a thin film of water. That means you need a circulating pump to push all the water around the tank.


8 years ago


sounds like the light answer has already been handled but ......you can actually get a UV aquarium steralizer. Least I think thats what it's called. My room mate has a fish tank and it got super green (algea) so he went and bought a UV filter, steralizer thing. Basically what I understand it is, is a pump that pumps water through it and inside there is a UV bulb/source that kills whatever as it gets pumped through it. I don't have any info on volume or strength, but it is ment to run 24/7. Maybe this could be an answer to your problem?

there are aquarium lamps that emit UV C specifically for the benefit of lizards and other reptiles that require it.As far as it's effectiveness through water is concerned I feel that since uv c will travel through clouds on it's way to us those exact same ray's will disinfect grey water only to a certain depth and thus would require that to be effective the water would need to be churned in the tank so all the water would at some point reach the top of the tank and come in contact with the uv ray's

Aquarium lamps are designed to simulate natural sunlight, not provide "lethal" UV. The penetration of UV diminishes with depth, so you would really need to sterilise it going in and keep it hermetically-sealed.
See here for details:
(it's effectively a "no", as far as the question is worded)