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Community and Q&A

Integrating rainwater collection system into house water faucets?

whitenack | Posted in Green Building Techniques on

Hi all,

Building a new house and at some point I would like to have a rainwater collection system. This system would route the gutter downspouts into an underground tank and then have a pump to distribute the water around the yard.

Thinking about how to distribute the water around the yard, I had the idea to connect the tank to my house water hydrants (house bibs, outdoor water hydrants, etc.).

The issue I am wrestling with is what about the times when the tank runs dry, or if I decide not to install the tank immediately. I’ll need water at the hydrant regardless. I had the idea of connecting the house water to the hydrants as a backup. I could put a valve ahead of the hydrants that would be opened or closed if needed, and could put another valve to cut off the line to/from the tank. My plumber didn’t like that idea, saying that the water from the tank would be dirty and there would be a risk that you draw some of that water up into the drinking lines. His solution was to have one or two hydrants that were dedicated to house water and then have other hydrants that were dedicated to rainwater. The problem with this is trying to predict which hydrants I will want for which purpose, and the expense of running lines side by side for two different water sources.

Is there another solution to this setup that I am not thinking about? Or is the only solution that you have to have completely different hydrants?

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  1. GBA Editor
    Martin Holladay | | #1

    I think that your plumber is right.

    In addition to paying attention to the common-sense concerns raised by your plumber, you have to follow the building code. Check with your local code authority before proceeding.

    Plumbing codes are fairly strict because this is a health issue. I don't think it's ever a good idea to mix water collected from your rooftop with water from a more conventional source (presumably, either municipal water or ground water from a deep well).

  2. Expert Member

    Just to add to Martin's post: If you are on a common system you can contaminate not only your water but your neighbours too. As well as keeping both systems separate, you should have back flow preventers on all outside hose bibs. Our codes mandate both my suggestions.

    While working as a small water systems operator I have seen whole mud puddles, and more worryingly pesticides designed to be spread from the end of a hose, sucked back into the house waterlines during a period of back pressure.

    Ask your plumber - I bet running separate lines is an insignificant cost in a plumbing budget.

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