Waste Not, Want Not:
 Saving Rain for Landscape Watering

Bonnie Duggan
Frederick County Master Gardener Program

"Into each life some rain must fall, Some days must be dark and dreary." After endless days of dragging the hose around my garden last summer, I take issue with Longfellow's view of a rainy day. A bit of "dreariness" would have brought a smile to my face and some relief from the water bill. And in the midst of serious drought, Friday afternoon radio disc jockeys would blather on happily about cloudless forecasts and "perfect" weekends as I uncoiled the hose for another round of watering the garden, watering the container plants, and watering the flower beds. Perspective has everything to do with how we see things, and last summer, my point of view was often the end of a garden hose.

So here we are, staring down the spray nozzle of another dry summer ahead; only it promises to be much worse than last year. Winter precipitation is critical to replenishing both ground level and underground water stores. Meanwhile, precipitation this winter has been inadequate, and coupled with increased demand, we are in a pickle. Restrictions on water use have already been imposed in some areas of Frederick County, and more are likely on the way. We're going into the growing season with the ground dry and our watering cans only partially full. What's a gardener to do? It is time we stop taking water for granted, change our usage habits, and find new sources.

New sources? Absolutely. I doubt that most of us think of rainwater as a new water supply, but in the truest sense, it is. If captured, stored and reused as needed, rainwater becomes a way to bridge the gap between showers in times of drought. Lawn and garden use of collected rainwater also decreases the demand on wells and the public supply. Since landscape watering accounts for a 40%-50% rise in household water use during summer months, the savings from reusing rainwater can be significant. Rain is free, but can't be ordered. It has to be taken as it comes then saved for a sunny day!

Saving rainwater is easier than you think, using a modern-day version of an old standby: the rain barrel. Chances are good that if you grew up on a farm, there was a rain barrel or two to supply everything from wash to bath water. When families depended on wells that were apt to run low or even dry, finding other sources of water always turned their thoughts heavenward.

The clouds build, the sky opens, the rain falls. Catch it. Save it. Use it! While they worked, those old rain barrels had problems that have been addressed by today's modern versions. Open barrels that were once breeding grounds for mosquitoes and watery graves for vermin have evolved into screened or closed systems that are cleaner and safer. While old barrels would spill over the sides when full, today's versions come with hoses that allow users to direct overflow water where it will be beneficial. Something old has become new and is finding its place as an indispensable modern day water management tool.

So let's look closer at what having a rain barrel or two could mean for you this summer.

A rain barrel is generally fed by a downspout which is the ending point for a section of gutter. If you look closely at your house, it should be obvious what section or sections of roof drain into each downspout. This area of roof is the "catchment" area.

For those of you who haven't thought about geometry (yikes!) for a while, roof area is calculated by multiplying roof length by roof width. If the roof area feeding a particular downspout measures 30 feet long by 25 feet wide, the area will be 30 x 25 = 750 square feet.

A general rule of thumb to estimate the amount of rainwater that can be collected is: for every inch of rain that falls on 1000 square feet of catchment area, 468 gallons of water will be collected. This amount takes into account loss due to friction, evaporation and spillage.

For example, let's see how much rainwater might be collected from a roof area of 750 square feet during a 1.5-inch summer shower. A whopping 526 gallons-enough to fill almost nine rain barrels!

If you only intend to fill a single barrel, that can be accomplished with as little as one-tenth of an inch of rain. Every gallon of rainwater collected and reused relieves the overtaxed public supply, saves wells, benefits the plants, and saves money! It is a savings account that pays big dividends.

Homeowners with small garden plots, flower beds and containers will find that a setup of one or two 60 gallon rain barrels is all they need.

When shopping for a rain barrel, some features to look for include: a spigot that can be connected to a garden hose, a fully screened intake to keep out mosquitoes and debris, a linking system to connect additional barrels, and a sufficiently large overflow hose so that excess rainwater can be carried away. A rain barrel should be adaptable enough for the user to customize it for their specific needs, and should work dependably--like your favorite pair of pruners.

Where do you go to purchase a rain barrel? Unfortunately, it is not easy to find one locally. There are many models available through garden supply catalogs and internet retailers, but at prices ranging from $100-$150, they are costly and expensive to ship.

Or you can build your own ...


Water-Wise Landscape Tips:

  • Build good soil that will adequately retain moisture and nourish plants.
  • Fertilize less and use more compost.
  • Mulch to a depth of 2-3 inches when the ground is thoroughly soaked to conserve moisture and prevent weeds.
  • Choose plants, especially native, that prefer less water, and group together those plants with similar water needs.
  • Reduce turf areas.
  • When watering, use soaker hoses or drip irrigation rather than inefficient sprinklers.
  • Condition plants to be more self-reliant by watering rarely and thoroughly to encourage roots to grow deeply into the soil.

General Tips for Water Conservation courtesy of The American Water Works Association:

Test for a leaking toilet by adding food coloring to the tank. If any color appears in the bowl after 30 minutes, the toilet is leaking. A single leaking toilet can waste as much as 200 gallons of water a day.

Use water conserving plumbing fixtures and water flow constrictors on sinks and showers. If you don't have a low-flow toilet, place two half-gallon plastic bottles filled with water in your toilet tank. This practice saves one gallon of water each time you flush.

Run dishwashers and washing machines only when full. (Dishwashers typically use 12 gallons of water per load and clothes washers use 20-40 gallons depending on the size load)

Take short showers instead of a bath. Baths can use from 30 to 50 gallons of water; showers use 5 gallons of water per minute, less if a flow constrictor is installed.

  • Check your water meter while no water is being used. If the dials are moving then there is a leak.
  • Don't run water continuously when washing dishes, brushing teeth, washing hands or shaving.
  • Avoid using a garbage disposal. Add kitchen scraps to the compost pile or trash instead.
  • For landscaping, choose either native or drought-resistant plants. Once established, they will require little if any supplemental watering.
  • Water lawn and gardens during the coolest part of the day. Use drip irrigation to apply water slowly exactly where it is needed. Collect rain from the gutter system on a house in a rain barrel to use for watering.
  • Use a bucket of water and a spray nozzle on the hose when washing cars. If a hose is left running continuously, more than 100 gallons of water will have been wasted by the time the car has been washed.

Read other articles on gardening in drought conditions