Thus, a homeowner in West Texas with a 2,000 square-foot roof can expect to collect about 10,000 gallons annually while his counterpart in East Texas with the same roof area can expect to collect over 55,000 gallons. Of course, this volume can be prorated for roof areas of a different size.

## How much water can I collect off my roof?

Approximately 550 gallons of rainwater can be collected for every 1000 square feet of collection surface per inch of rain. To estimate amount collected in one year, take the square footage of your collection surface, divide by 1000, multiply by 550 and then multiply by the average annual rainfall for your area.

## How do you calculate rainwater runoff from a roof?

How Much Rain Water Runs Off Your Roof?

- Take the dimensions of the footprint of your roof and convert them to inches. (So, a 50′ x 20′ roof is 600″ x 240″.)
- Multiply the roof dimensions by the number of inches of rainfall. (In this example, 600″ x 240″ x 1″ = 144,000 cubic inches of water.)

## How many gallons of rain come from roof?

Every square foot of roof space collects . 6 gallons of water in a 1 inch rainfall.

## How do you calculate rainwater volume?

Formula: Area (Length x Width) x Rainfall

- A = Length of the roof area.
- B = Width of the roof area.
- C= The amount of rainfall in inches.
- The formula is A x B x C = Water Volume.

## How do I calculate roof drainage?

Take the roof’s total square footage and divide by the total square footage handled by one drain. The result is the number of drains needed. For example: 50,000 / 4,400 = 11.36; or 12 drains required.

## How fast do rain barrels fill up?

It’s common for about 1/8″ inch of rain to fall each hour during a moderate rainstorm. That means that a 500 square foot roof can fill a properly installed 50-gallon rain barrel in about one hour.

## How do you calculate runoff?

Simple, straightforward methods of calculating runoff can tell you the amount of water that storms bring to the earth. For a given surface area such as a roof or yard, multiply the area by the inches of rainfall and divide by 231 to obtain the runoff in gallons.

## How do you calculate rainfall on a roof?

This capacity can be calculated using the following formula: Annual rainfall (in millimetres) x Roof surface area (in square metres) = Roof catchment capacity. This is an important figure to understand so you can design a Rain Harvesting system and choose a tank size that will meet your water volume requirements.

## How many liters is 1 mm of rain?

With a rainfall of 1 mm, every square metre receives 1 litre of rain water. A rainfall of 1 mm supplies 0.001 m3, or 1 litre of water to each square metre of the field. Thus 1 ha receives 10 000 litres.

## How fast does a 55 gallon rain barrel fill?

How long does it take to fill my rain barrel? It depends on how much roof area drains into your barrel. The average size roof area that drains into one downspout is 300 sq ft or 30 ft long by 10 ft wide. It takes only 0.3 inches of rainfall to fill one, 55 gal barrel off of 300 sq ft of roof!

## Are rain barrels worth it?

Many arid or drought-prone regions have restrictions on lawn watering, and a rain barrel system can be an excellent way to get around these rules. If water use is expensive, capturing precipitation to use in the household can also be worthwhile. … Considering this, a 4,000-gallon system might cost $15,000.

## How many gallons of water does it rain a year?

averages about 45 inches of precipitation per year; multiplying this by the 2.293 billion gallons shown in the table as the number of gallons in 1 inch reveals that some 103.2 billion gallons of water fall on Atlanta in an average year.

## What is MM IN RAIN measure?

The most common rainfall measurement is the total rainfall depth during a given period, expressed in millimeters (mm). For instance, we might want to know how many millimeters of rain fell over the course of 1 h, 1 day, 1 month, or 1 year. You can easily get a rough measurement of rainfall depth at home.

## What is the volume of 1 inch of rain?

A standard Weather Service rain gauge is a cylinder eight inches in diameter, so one inch of rain would have a volume of about 28 ounces or about three cups. Measurements of very large volumes of water, such as lakes or reservoirs, are expressed in acre-feet.

## What is a lot of rain?

Heavy rain: Greater than 4 mm per hour, but less than 8 mm per hour. Very heavy rain: Greater than 8 mm per hour. Slight shower: Less than 2 mm per hour. Moderate shower: Greater than 2 mm, but less than 10 mm per hour. Heavy shower: Greater than 10 mm per hour, but less than 50 mm per hour.