Harvesting Rain

A Look at Available Solutions

You have a lot of options if you want to harvest rain these days. The basic concept is to collect the rain coming off your roof through the downspout and store it for later use. Which ever option you chose for your home, harvesting rain water will reduce your use of municipal or well water and help our local environment.

So why should you invest in a rain harvesting system?

• Rainwater is a natural and vital renewable resource so why not collect it and reuse it for irrigation or better yet, plumb it into the house for flushing toilets and washing clothes for any non potable use.
• When you reuse rainwater for your plants they will respond better because rainwater is PH neutral, has nitrogen for a natural fertilizer AND it is not chemically treated.
• By irrigating with rainwater you are offsetting the municipal water supply and preserving our drinkable water for future generations.
• Controlling runoff helps to protect our rivers and streams from pollutants. By collecting rainwater coming off your roof you are slowing down the storm water and by reusing it you are helping to recharge ground water.
• You are saving the energy it takes to treat the water to make it safe to drink. California uses 20% of its state power consumption to treat and move water.

How Much Potential?
When I show the equation for collecting the full potential of rain from roofs, most people are amazed. Simply measure the roofs footprint (pitch doesn’t matter) and multiply by .625 to get the amount of collectable water coming off the roof from one inch of rain. In North Carolina we average about three inches of rain per month. So, if your home has 2,000 feet of roof area then you have approximately 3,750 gallons of free water coming off the roof per month. That’s 45,000 gallons of free, ph neutral, chemically untreated, natural rainwater each year.

The math: (2000 x .625) x 3 = 3,750 then multiply by 12 to get the annual potential of 45,000 gallons.

Rain Barrels
The first and easiest option is a rain barrel. They range in size from 55 to 400+ gallons. The rain barrels are used typically for hand watering and drip irrigation through a soaker hose, this is just a teaser for some people.

Rain barrels are great but are obviously not capable of storing all of the rainwater coming off of even small homes. They are ideal for small gardens and for smaller water demands. Rain barrels range from $50 to several hundred dollars so they are very easy and affordable.

Cisterns
The next step is a cistern. Cisterns can be as small as 200 gallons or large enough to contain millions of gallons of water. They can be above or below ground. Below ground cisterns are a very popular choice as they can be hidden and don’t take up valuable yard space, especially in neighborhoods where yard space is limited. Below ground systems require excavation and tend to be more expensive to install as a result. We differentiate between rain barrels and cisterns when you add mechanical elements to the system: pumps, level indicators, filters, etc..

Above Ground Cisterns
Above ground cisterns can be made of plastic, metal, or concrete. They can be hidden or act as architectural features. A basic set up only requires a roof, gutters, some type of pre-filtration and a tank. That’s it. Once the tank is full, there needs to be adequate capacity for overflow, whether it’s a rain barrel or larger system. Consider where the over flow will go. We like to use rain gardens to capture the overflow so the rainwater is buffered, kept on site and allowed to soak into the ground. This not only helps you plants and lawn, it helps protect our streams and rivers by slowing down the storm water runoff. The great news is that you are not only helping with local water quality you are also collecting water to use how and when you want. Water you collect and store is not subject to water restrictions. It’s your free water!

Below Ground Cisterns
Below ground systems can be placed below patios or even driveways. They are great space savers and can be almost invisible to the unsuspecting observer. Placing your cistern underground also help address the problems with potential freezing. While our winters are not usually that bad any above ground systems should be winterized.
Making a Selection

Consider your water demands. This will determine the size system you need. Do you just need to water house plants, or do you need to irrigate a large yard and have water to wash your car? Do you need water for fire protection? Next, consider any site restrictions - do you have the space to excavate or is there a spot behind the house or garage to place a tank? At the end of the day, we all have budgets. Above ground systems are less expensive because in most cases tanks can be rolled into place and a pump added very easily. Above ground systems don’t necessarily have to have a pump - water does have to run down hill though so this will be dependent on where you will site the tank and where the water is needed. Below ground systems will almost always require a pump - which will supply pressure to run an irrigation system, sprinkler or allow you to wash your car but is an expense that must be considered. Both types of systems are great for delivering all or some of your non-potable water.

Mike Ruck owns Rain Water Solutions, Inc. of Raleigh along with his wife Lynn Ruck.