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Tips for Rain Barrels and Cisterns

Behnke Nurseries is located in Prince George’s County, Maryland.  To reduce stream pollution and pollution entering the Chesapeake Bay, Prince George’s is actively working to reduce runoff during storms.  [Among other things, heavy runoff may overwhelm sewage treatment systems.  This is discussed previously here and here.]  Surrounding counties in Maryland have similar programs, each with a different name.  Ours is called the Raincheck Rebate Program.

Behnke’s was selected as a site to install examples of the seven types of projects you can do to earn a rebate.   We have discussed the Rain Garden several times, and are moving on to Rain Barrels and Cisterns.   You can find out all about the program here.

Rain Barrels and Cisterns are waterproof storage containers designed to capture water falling on a roof surface and intercepting it before it runs through the downspout to the ground.  It’s easiest to think of a cistern as a big barrel.

rain-barrelsRain Barrels at Behnke’s

Installing a rain barrel is pretty easy and they are not very expensive.  The rebate is $2 per gallon stored; so a 50 gallon rain barrel should earn a rebate of $100.  The aggregate rebate available through this program is $ 4,000 for homeowners.  Installing a rain barrel or several is an easy way to get a rebate, and should go a long way toward paying for the cost of the barrel.  My understanding is that this particular rebate is pretty easy to process.    You must fill out the application form, of course—in advance—and eventually you will need to provide a receipt, but you shouldn’t need to get anything inspected.

A few things to bear in mind.

  • Water is heavy. As I learned it at my father’s knee: “A pint’s a pound the world around, except in England, where a pint of water weighs a pound and a quarter.”  [More or less; the Imperial pint is 20 ounces, the American pint is 16 ounces.  So if you are in a pub in London, a pint of their best bitter ale is bigger than a pint of ale in Baltimore, which justifies the trip in my opinion.  But I digress.]
  • The weight thing means that your barrel needs to be on a solid support. A fifty gallon barrel of water weighs 400 pounds, plus the weight of the barrel, of course.
  • Water flows downhill. Remember that fact when you are draining the barrel to use the water in the garden.  There is no pump, so the pressure is generated by the weight of the column of water in the barrel.  If the end of the hose is higher than the level of the water in the barrel, it stops flowing–it’s just a siphon.   If if you can put it up on a sturdy platform of bricks or something, it will have higher pressure than it will have if just sitting on the ground.
  • The more water in the barrel, the more pressure. Water will flow faster when the barrel is full than it will when it is nearly empty.
  • It’s rain water but it isn’t drinkable. It’s got all that dissolved bird poop and stuff in it; whatever came off the roof and dissolved in the water.
  • To help keep the water ”fresh” you need to screen debris from falling into the barrel; this will be part of the barrel kit.  You don’t want 50 gallons of water that smell like a gutter.  You also want to use it regularly to keep it turning over.
  • The screen also is there to prevent mosquitoes from laying eggs in the water.
  • You can link barrels in a series. As the first fills it can overflow into the second, and so on.  The example here at Behnke’s has 3 barrels in series.
  • Click here to learn all about rain barrels.

cisternCistern at Behnke’s

As far as Cisterns go: cisterns are big.  The minimum storage size for a rebate is one that will capture at least 250 gallons.  With the whole “water is heavy thing”, there is a lot more to consider when installing a cistern.  With the weight of the container itself, for example, a water-filled thousand gallon cistern might weight as much as 9,000 pounds.  That is going to require a solid foundation, e.g., concrete.

Among other things:

  • you have to have a big enough roof to capture enough water to make it worthwhile.   There is a calculator on the website that will take you through that math.  No sense getting a thousand gallon cistern if you are never going to get enough rain to fill it.
  • You have to be able to use the water fast enough to make it worthwhile, I mean, the whole idea is to capture storm water; you’d like the cistern empty for the next storm. A thousand gallons of water is a lot of water; you probably are going to want to have a pump installed to boost the pressure [which of course, requires electricity] so you can use the water more efficiently.
  • Personally, if it were me, if I were going to do this, I would likely bring in a contractor; however if you are mechanically inclined, you can do it yourself but you are going to have to jump through more hoops to make it all work. I have a modest amount of handiness–I can nail in a screw with the best of them– but this is above my skill set.
  • Same deal, $2 per gallon rebate available.
  • Cisterns are probably better for commercial buildings, or schools, churches, community centers, that sort of thing. If you fall into this category, you can get up to $20,000 back [again, the aggregate over all projects] and you’d have plenty of “free” water to keep those foundation plants alive around the building.
  • Click here to learn all about cisterns.

When my parents built a home on a rather arid piece of ground on the Caribbean island of Montserrat back in 1967, one of the things they added to the house was a concrete cistern (cisterns are now most often made of plastic).  Somewhere along the way, I think the bits about “needs to be screened” got lost; perhaps it was screened and the screen rusted away.  I just recall that at some point they gave up on it and eventually drained and sealed it after it became a weekend spa for tiny tree frogs that would find their way in to lay their eggs, yielding zillions of tiny (yet very loud) offspring.

So if you are thinking about a cistern, carefully consider placement, use the water between rainfalls, and screen out the critters.

by Larry Hurley, Behnke horticulturist

Larry Hurley, perennials specialist for Behnke Nurseries (now retired), started with Behnke’s in1984. Larry enjoys travel, food and photography. He and his wife Carolyn have visited Australia, New Zealand, Thailand, Brazil, South Korea and much of Europe. Their home is on a shady lot where a lot of perennials have met their Maker over the years.

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