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Rain Water Collection Filtration System? Answered

We are in the middle of  designing a  rain water   collection system for a  commercial  building   that    includes:
1.  a  2500  gallon  in  ground  tank
2. 1/2 hp  submersable  well pump
3.simple  float  valve to maintain  minimum   water level  during  drought
What we  are     trying  to figure   out   is  to exclude   purchasing a  complicated  expensive   store bought  filtration   system we were   trying  as we always  do to  keep things  simple.   we have to   provide  sometype of  secondary filtration  system    to  aereate  the  water as well as  clean  it   in order to  run  to  our  toilets. 
Whatwould  be wrong with using a   small  pool filter  set   in a  1 hour  a day   cycle  that  would   provide  oxygen  to  the water ? Also we were looking  at   using  one of  the floating   chlorine  tablet  holders  like  a   pool would  use  to   maybe   kill  any pathegons    that would  be in  it.
We  realize this is  too simple  to    not have  some   down side  so  all    opinions  and help would be greatly appreciatted.


You want the tank in/on the roof, with a mains (float-valve) feed at let's say 25% capacity. Flush-toilets ought to drain enough volume  that you wouldn't need to condition the water. If the tank runs low it fills (to 25%) from the mains.


This tank would be under ground thus the reason for the 1/2 hp pump . the plan is to simply use the pump to supply toilets irrigation of the flower beds or any other purpose we can come up with. We are thinking exactly the same on the float valve 25 % . This woudl allow any particles that escape the filtration to seddle to the bottom. Thanks for your response.

Settle it BEFORE you filter it. Use a weir system

I think I'd
a.) Make sure its DARK in the tank
b.) Aerate it gently.
c.) Make the tank as sealed as possible from insect life.

yes the tank and all hoses are dark and sealed. I will just drop back and keep it aerated and go with it . thanks alot


6 years ago

I would be completely flabbergasted if any building official or health department would approve a system like that for your stated purpose.

NC signed a bill last week allowing rain water to flush toilets in efforts to reduce demand of potable water. Now we are not drinking the water and the only use will be toilets and irrigation , but i have concerns about providing some oxygen and further filtering . Just d not want the water to turninto "Gray water" and havea odor.

If you ain't drinking it, and it looks clear, and you store it in the dark, and you are only using it for toilets, you don't care about pathogens.

Nc hwere i lived just passed a bill to allow toilets to be flushed from rain water. My only concern is that if the water in the tank become stagnate . i visisted a house once that had 12 people living in it and the toilets flushed with ran water. They use a lot more water than i would. That is my only concern adn only reason for even circulating it. Thansk fo rthe response

.  There is no need to inject Oxygen into the water, simple aeration should do the job.
.  As others have mentioned, if you don't plan on drinking the water, it doesn't have to be all that clean or sterile. You may need to do some disinfecting to keep the smell from getting objectionable.
.  Investigate aquarium undergravel filters and other sand and/or gravel filters if you really need to do some filtration.

If you only need to flush with it then I see no reason to do much more than filter large particles out - a sand/gravel filter should do that.


6 years ago

Buildings that have exposed water collectors or roof cooler systems like SF
city hall handle 2 to 5 amps DC in each water to each tower and these
consumable 4 conductors are 8" long 2" wide 1/4" thick each. and must be
reverse polorised every hour.  Water collecting roof tops also collect dust
of meteors in space that disintegrate in our atmosphere and dust to get in
the sludge which can be resold.