Rain water collection system basics

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gaijinfarmer
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Rain water collection system basics

Postby gaijinfarmer » Mon Nov 27, 2017 10:54 am

I have a couple tanks that I'm interested in repurposing for rainwater collection. There are a number of Japanese sites about this but to be honest I start to feel a little lazy when faced with that wall of text.

I'd hope to use it for laundry, yard, and car washing. Does anyone have info on the best simple filtration systems, and what level of sanitation is necessary to maintain for those uses?

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Zasso Nouka
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Re: Rain water collection system basics

Postby Zasso Nouka » Tue Nov 28, 2017 6:44 am

Depends how clean you want it, if you just want to remove particulate matter the easiest filter might be something based on sand and a cloth to keep the sand from going further down the line and an ability to reverse the flow every now and then to flush it out.

If you are going to pressurise the system you could incorporate one of these filters or mesh screens that are used in drip irrigation.

Irrigation Filters

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Re: Rain water collection system basics

Postby gaijinfarmer » Thu Nov 30, 2017 4:59 pm

I was thinking more along the lines of rooftop to gutter collection, with a first flush valve to get rid of particulates and filters to get rid of debris.

Piping to the laundry shouldn't be too hard since it's near a soft outside wall. But toilets might be tricky.

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Re: Rain water collection system basics

Postby Zasso Nouka » Fri Dec 01, 2017 6:18 am

I'm not an expert on this but perhaps the easiest filter setup if between gutters and storage tank so you are filtering the water before it is stored and then if the tank is high enough gravity feed to everything else. That way the filter isn't restricting the flow to your toilets and washing machine but the drawback there could be that in torrential rain situations the filter might have too slow a flow rate and the rain backs up and overflows your gutters.

What about a settlement tank then feeding into a sand filter and on to your main storage tank with an overflow on the settlement tank ?

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Re: Rain water collection system basics

Postby gaijinfarmer » Fri Dec 01, 2017 10:32 am

Would that whole thing be able to be gravity fed?

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Re: Rain water collection system basics

Postby Zasso Nouka » Sat Dec 02, 2017 6:17 am

Depends how high you can mount it and how much pressure you need I guess

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Eric in Japan
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Re: Rain water collection system basics

Postby Eric in Japan » Mon Dec 04, 2017 9:31 am

You should put on a first flush diverter, to keep most of the sediment/pollen/bird droppings/etc that is on your roof out of the water storage.
There are lots of Youtube videos about it. I like this one:
https://www.youtube.com/watch?v=78SfQt9IIQs
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Rain water collection system basics

Postby Eric in Japan » Sat Dec 09, 2017 12:18 am

gaijinfarmer wrote: with a first flush valve to get rid of particulates


Don't know how I missed that gaijinfarmer- sorry about the unneeded post
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Rain water collection system basics

Postby gaijinfarmer » Mon Dec 11, 2017 1:16 pm

No problem Eric, thanks for the video! I'd only seen products for this purpose, hadn't found anything DIY yet. ;)


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