Rain Barrels Save Water, But Is It Clean Water?

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Lifestraw filters are good basic emergency supplies

What’s On The Average Roof?

With the rainy season on the horizon (hopefully), I recently wrote an article about using water saved in rain barrels safely and have been answering many questions ever since. Several people wanted to know if they could use wooden barrels, rather than the ubiquitous plastic ones sold today. Well, sure, if you can find one that holds water and has never held anything toxic or nasty. Sadly, wooden barrels aren’t common anymore, and if you do find one, unless it was intended to be used for aging wine or whiskey, it may not even be water-tight. For one thing, wooden barrels need to stay full of water or they dry out and leak like crazy, and even after they get refilled, it can take a while for the leaks to close up. What’s more, sometimes a drying barrel will warp, and the metal hoops that hold wooden barrels together may fall off or corrode and crack, ending the useful life of the barrel. Finding new ones isn’t easy, unless you live near a brewery; the art of coopering is growing rare and nearly all barrel makers now work for breweries that favor traditional aging techniques. And no, there’s no way to put two half barrels back together; most of the half-barrels sold as planters are made to be filled with soil, not water, and are not really half of a complete barrel at all.

For centuries, wooden barrels were the shipping containers of choice, holding dry goods like nails and gunpowder as well as salt fish and beef, tobacco and tea. Some even held liquids, from molasses to wine and spirits. Empty barrels were often placed under eaves or at the ends of wooden gutters to capture water off the roofs of barns and outbuildings and homes. The captured rain water was a handy source of clean(ish) water that was usually nearer to the house than the well (something much appreciated by children, who were the usual water fetchers). Rain barrel water was often used to irrigate flower beds and smaller vegetable patches near the home, and in the rainy season, might be used for laundry and even for the family’s Saturday night baths.

Up On The Roof

Rain barrel water wasn’t usually used for drinking and no wonder. Even when roofs were mostly made of wooden shingles or slabs of slate, they were still pretty dirty places. In hotter climates, roofs might be less apt to accumulate the thick mosses and lichens so abundant in cooler areas, which make perfect hosts for all sorts of unpleasant pathogens. Even so, roofs everywhere are visited by birds, rats, raccoons and/or other regional critters, all of which leave their droppings behind when they wander away. Such droppings can include a generous assortment of pathogens and diseases, many of which survive quite well despite the heat and drought on a hot rooftop, being able to go dormant in various ways. Many will positively thrive once they hit the rain barrel, lingering invisibly in the relatively warm, still water.

I know I’m getting a little geeky (again), but seriously, there’s a lot of unsavory stuff in most rain barrels. Besides those natural yet dangerous substances, today’s rainwater can leach chemicals from modern roofing materials, from manufactured shingles to treated wooden shakes. Our rooftop runoff can now include asphalt, tar and glue, petroleum by-products, glass particles, lead, and more. Metals roofs can shed zinc, copper, and aluminum as well. Some of those chemicals can react with water, especially acidic rain, and bind the harmful substances so they remain hidden but still effective in our water barrels. In addition, rainfall increasingly contains tiny plastic particles that accumulate in our bodies, with both known and unknown effects (and none of them likely to be good).

Finding A Filter

Several readers wonder if rain barrels can be a source of drinking water in an emergency. Well, no and yes: If you are assuming that you can just dip and sip, then no. Really no. If you can filter that water, it might become safe, but getting there requires more than a simple screen type filtration system. First, any filter must strain out bird and animal droppings, pollen, dust and dirt, slime molds and other unsavory things, all of which will affect the quality and cleanliness of the rainwater. Beyond that, it’s best to have a filtration system that is also able to capture lead, copper and other toxins as well as bacteria, especially if your rain barrel is not covered, as standing water nearly always develops various kinds of gunge, visible or not.

Some people feel that it’s enough to filter out particulate matter before using rain barrel water for irrigating plants, since many plants and soils are able to effectively purify water, but if it’s going to be used on edibles, or serve as emergency drinking water, better filtration is wise. A filter system for stored water should include a pre-filtration stage of at least 30 micron rating, an automatic filter backwash cleaning function, and a way to remove the backwash water (usually not a lot) from the filters. Polypropylene & ceramic cartridge type filters can remove sediment and bacteria, but not viruses, while activated carbon filters are very good at removing and/or reducing odors and unpleasant tastes, as well as some chemicals including iron and hydrogen sulphide, but not bacteria or viruses. Most micro/ultra filtration membrane systems can remove sediment, bacteria and viruses. Hopefully it’s also obvious that rainwater capture tanks and plumbing materials must be rated as suitable for contact with drinking water.

Barrel Cleaning & Personal Emergency Filters

August is a good time to empty water storage containers, a task that should be done annually. Use unfiltered water freely on ornamental garden beds and lawns or for washing the car, patio or deck furniture. When setting up a new water barrel, rinse it out with bleach water, making sure any plastic bits are flushed out. To keep stored water potable for up to a year, add 4-1/2 teaspoons of bleach per 55 gallons of water. Store the barrels in a shaded place where they won’t heat up in summer weather. If the hose attachment is near the very bottom of the barrel, set the barrel on blocks to make it easier to get the hose on and off (this turns out be be quite important!). To clean rain barrels, empty them completely, then scrub until clean and rinse them out with a mild bleach solution.

If you envision needing a lot of water during a prolonged emergency (think tsunami, etc), consider more complex filtration systems such as the Lifestraw Community water purifier, which removes most particulate matter. There are also smaller units, including personal units designed to be used by a single person. These supposedly never expire and the membrane filter can process up to 1,000 gallons, which is at least a few year’s supply. Onward, right?


This entry was posted in Birds In The Garden, Drainage, Garden Design, Health & Wellbeing, Moss, Sustainable Gardening, Sustainable Living and tagged , , , . Bookmark the permalink.

2 Responses to Rain Barrels Save Water, But Is It Clean Water?

  1. Leesa says:

    Hi Anne, I’m wondering if you’ve ever heard of this water filtration system? https://www.berkeyfilters.com. We have one and I’ve heard it can be used to filter almost any kind of water. Also, I have 2 cisterns that I installed on the N side of my house a few years ago. I have been using the water for some of my herbs and a few tomatoes that are in pots. It never occurred to me that this water would not be good for watering edibles. So thank you for this article! I’ll need to do some research on how to filter the water going into the cistern! I’m a big fan! Thank you!

    • Ann Lovejoy says:

      Hi Leesa, yes, I’ve herd good things about Berkey filters but haven’t owned one (yet; might be a good time to invest!).

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