• Jonathan Meier

Using rainwater inside the home: What you need to know

Updated: Feb 8, 2020

Thinking of plumbing rainwater inside your home? Great idea... but is it legal? The answer -- unsurprisingly -- is a bit complicated.

(Author's note: This article is an extension of a similar article we wrote last year entitled, "Is rainwater harvesting illegal?")

If you are wanting to plumb rainwater inside your home, whether it's to supply toilets or your kitchen sink, there are a few things you'll need to know. First, do you have access to a public water supply? If you live in town, the chances are quite high that you do, even if you don't (or aren't planning to) have a municipal water tap on your property. If, however, you have access to public water from a tap, then, unfortunately, you may have a bit of an uphill climb to get approved for bringing a rainwater supply into your home. Specifically, the EPA prohibits a home from having both a municipal and a private water supply.

Before you hop on social media and type up a rant about rainwater being illegal, please understand that the backbone of this regulation is justified: It would be a bad idea to let "DIY John" from down the street hook up his unfiltered rain barrel into house plumbing supply. In doing so, he could introduce bacteria into not only his own house, but, if there was a sudden back pressure in your block's water main, he could send bacteria into your water supply, too. It is a dangerous game, and in all our years of doing this line of work, we have encountered some folks who violated the law and have done just that -- risked the health and safety of themselves and their neighbors.

Don't despair, though! There is still hope.

While it is not permissible to have two or more primary water supplies if a public water supply is available for your home, chances are very good that you can still work with your local building and zoning/plumbing department and get approval for bringing in rainwater to, say, feed "non-potable" fixtures (e.g., toilets, laundry, and outdoor spigots). Often times, a water department will allow this type of usage provided that a system has the following:

1) An approved backflow prevention device on your municipal water main (this generally has to be inspected annually). This device prevents rainwater from contaminating the municipal water system;

2) Completely separate plumbing going from rain cistern/tank to your non-potable fixtures (i.e., not connected at all to any branch in your home that is supplied by municipal water);

3) A water meter on the rainwater supply. This is only the case if your home is hooked up to a city sewer system. Remember, the city charges for every gallon of water that drains into your sanitary sewer. Normally, they calculate that by just seeing how much water you've used for the month/quarter. However, if you're using rainwater to, say, flush your toilets, they need to be able to know how much you're using so they can see how much "other" water is being flushed down their system.

With these three aspects present, it makes it hard for a water department to disallow your system, and chances are very good that you'll get approval, especially if you propose these three things in your design in your initial presentation to the water department (they'll be impressed!).

Given these restrictions, is it cost-effective to bring rainwater into your house to, say, flush your toilets and do laundry? In our opinion and experience, we actually try to talk our customers out of going down this path because we don't think it is cost-effective or a great use of resources (and that's coming from people who are in the business of selling rain systems!). Using rainwater indoors if you have access to a public water supply is a huge endeavor, especially if you are trying to retrofit an existing home/building. If water conservation is your end goal, then buying low flow, dual-flush toilets are a better way to go. However, if you are doing a new build, then planning for a secondary, non-potable water supply is feasible and may not add that much more to your end construction costs. At the very least, using rainwater for outdoor watering only is always a great solution and will generally give you a quick return on your investment.

What happens if you don't live in an area with a public water supply?

If you don't have a municipal water supply for your home, your chances of putting in a rainwater harvesting system to supply your house just increased exponentially! In fact, we don't know of any state in the country at this point that would not allow you to harvest rainwater for your primary water supply. Now, there may be regulations (as in Ohio), but rain cisterns are allowable and, in fact, are quite common, especially in the Ohio region where we still today have more rain cisterns in use per capita than any other region of the country. Contact us today and let us help you design and implement an effective system!

As always, thanks for reading.

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Columbus, OH 43223


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