Rain water collection system basics

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Zasso Nouka
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Re: Rain water collection system basics

Post by Zasso Nouka »

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

Post by Zasso Nouka »

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

Post by Zasso Nouka »

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

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Re: Rain water collection system basics

Post by Eric in Japan »

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:
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Eric in Japan
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Re: Rain water collection system basics

Post by Eric in Japan »

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

Post by farmingnoob »

With yesterday's relentless rain, I started thinking maybe I should be harvesting this free water for use in the garden.

Does anyone have any suggestions for cheap water tanks (new or used)? I'm thinking about harvesting between 500 to 1000L.

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Re: Rain water collection system basics

Post by Ibaraki llama »

Have also been researching this without much progress. I'd like to use for watering the garden. Also thinking of putting a sprinkler system in.

In terms of tanks you can get 500L tanks (not specifically for rainwater but would serve the same purpose I think) from DIY stores, not sure about 1000L ones. Otherwise might have to import from Australia or somewhere (they have some nice 1000L slim line ones designed for residential housing). I haven't seen a wide range of pumps in Japan, but I've been looking at ordering from the US.

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Re: Rain water collection system basics

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Re: Rain water collection system basics

Post by Zasso Nouka »

Zaimondos wrote:
Tue Jun 11, 2019 4:13 pm
I haven't seen a wide range of pumps in Japan, but I've been looking at ordering from the US.
Monotaro have you covered there. Personally I'd go with an electric pump rather than petrol driven, way more convenient and don't have to worry about running the petrol tank dry every time you use it (to avoid water building up in the fuel and rusting the engine). Looking through that list the Jet Mate is specifically design for watering applications but there are other choices.

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Re: Rain water collection system basics

Post by Ibaraki llama »

Great, thanks.