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Rainwater Collection Systems

Rainwater Collection
These days it seems that everything is going up – the cost of food, gasoline, electricity, water – that is, everything except the amount of rainfall in East Tennessee. Most of us want to keep our lawn and garden healthy and vital, but the cost of using utility water is just too prohibitive. And, it places an additional drain on our valuable natural resources. In the old days, folks collected rainwater in cisterns and other containers to meet their needs for water. Well, perhaps they were smarter than we sometimes give them credit for – it seems that for every 1,000 square feet of your house’s footprint, one inch of rainfall results in about 600 gallons of runoff from your roof. With an average annual rainfall of 47 inches, a typical home with a 2,000 square feet footprint experiences around 56,000 gallons of roof runoff per year. Imagine the benefits of using that FREE water on your lawn or garden during dry spells, while at the same time doing your part to have a positive impact on the environment.

The Superior Barger and Sons Solution
Perform an internet search on “rainwater collection” and you will find a number of products on the market. Only problem is, almost all commercial products are designed for above ground installation – and we think you will agree that many are really ugly! Furthermore, capacity is a major issue. Tanks holding only a few hundred gallons aren’t much benefit during an extended dry spell. In contrast, Barger and Sons offers an esthetically pleasing rainwater collection system that is installed below grade with a capacity tailored to meet your specific needs. Manufactured using the same superior quality methods as our other precast concrete tanks, our rainwater collection systems offer decades of watertight performance. Collecting rainwater is one thing, but it is not beneficial until you distribute it where it is needed. A small electric pumping system for distributing the collected rainwater may be needed.

When Should I Install a Barger And Sons Rainwater Collection System?
The best time for installing a rainwater collection system is when you build a new home. At minimal cost, the output from your gutter downspouts can be routed by your contractor to a Barger and Sons rainwater collection system. Already have a home? You can usually retrofit a rainwater collection system to your existing gutter system.

Method to help size your underground storage needs:

Step 1
Determine the amount of square footage used to collect rainwater. This is also referred to as the footprint of your house in square feet. For example, if your house is a one story house with a footprint 50 feet by 40 feet, 2000 square feet can be used as the area to collect rainwater. If your house has more than one story calculate the square footage of the largest floor and use that number. While this does not account for roof hangover and the slope, both giving more area to collect rainwater, it gives you a close approximation.

Step 2
Decide what kind of rainfall event you want to prepare for. Do you want to design for a 1”, half-inch, or 2” rainfall event? Once you decide, calculate the storage in gallons needed to hold the rainwater.

Step 3
You can reference Chart 1 to calculate your required storage or you can multiply your collection area (square footage) by your designed rainfall event multiplied by 89.76. i.e. 2000 square feet x 1 inch x 89.76 = 1,247 gallons per 1 inch of rainfall.

Step 4
Are you irrigating a lawn? If so, how many acres or square feet is the area to be irrigated? What kind of rainfall event do you want to simulate?

Let’s assume one-half (0.5) acres is the size of the lawn to be irrigated.

Step 5
Using 0.5 acres from
Step 4, choose the rainfall event you would like to simulate. We will choose one-half (0.5”) inch rainfall event.

Step 6
Calculate storage (gallons) needed to water lawn according to Step 4 and Step 5. Refer to Chart 2 or multiply the number of acres by the simulated rainfall event (0.5 inch) multiplied by X. This result gives you the amount of storage need in gallons of water. i.e. 0.5” rainfall event x 0.5 acres x 27154.4 = 6,788 gallons

Compare the results from Steps 3 and 4 to see if this is desirable and repeat the calculations changing the information as necessary until you are comfortable with the design.

Step 7
Call us for a rainwater collection storage quote with the information from Step 4 that will include everything you need to store your rainwater.

Step 8
1” of rainfall per week on your lawn is generally recommended. We recommend installing two weeks worth of storage starting out. Modules can be added later if additional storage is needed.
Table 1

Foot print of house (sq. ft.)

Rainwater collected for every 1" of rainfall (gallons)