# How Much Water Comes Off My Roof When It Rains?

## How do you calculate rainwater collection on a roof?

To calculate how much rainwater can be harvested, multiply your rainfall (mm) by your roof surface area (m2) being used to catch rainwater.

The resulting number represents how many litres of water you can expect to collect..

## How much water equals an inch of rain?

27,154 gallonsOne inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons. An inch of snow falling evenly on 1 acre of ground is equivalent to about 2,715 gallons of water.

## How do you get water out of your roof?

Rainwater harvesting is collecting the run-off from a structure or other impervious surface in order to store it for later use. Traditionally, this involves harvesting the rain from a roof. The rain will collect in gutters that channel the water into downspouts and then into some sort of storage vessel.

## How is rain fall calculation?

Here’s what you’ll need to do:Measure the diameter of the bucket at the level of the rain. … Measure the diameter of the bucket at the bottom in the same way.Calculate the average of the two diameters.Divide by two to find the average radius.Find the average volume of rain = Depth x radius x radius x 3.14.More items…

## What is a lot of rain?

Moderate rain: Greater than 0.5 mm per hour, but less than 4.0 mm per hour. 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.

## How many Litres is 1mm 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 long is rain water good for?

Rainwater that has been properly purified (i.e. UV, Ozone, chemical) can be stored indefinitely as long as it is stored properly in an airtight container or system (i.e. pressure tank and piping). It is the opening of faucets or top of containers that could possibly introduce bacteria into the system. 33.

## How long can water sit in rain barrel?

Rainwater can be stored from anywhere between one week and indefinitely. The more consideration you put into your storage system – using the right materials, preventing algae and mosquitos – the longer your rainwater’s shelf-life.

## Is 1 to 2 inches of rain a lot?

Rainfall rate is generally described as light, moderate or heavy. Light rainfall is considered less than 0.10 inches of rain per hour. Moderate rainfall measures 0.10 to 0.30 inches of rain per hour. Heavy rainfall is more than 0.30 inches of rain per hour.

## How many inches of water should I water my lawn?

When watering an established lawn, it’s typically recommended to water until the top 6 to 8 inches of soil (where most turfgrass roots grow) is wet. Most lawns need 1 to 1.5 inches of water per week—either from rain or watering—to soak the soil that deeply.

## How many gallons is two inches of water?

I read somewhere, 2 inches = 2 gallon. Another article says 4-5 gallons per week in hot weather.

## What is the meaning of 1 cm rain?

If it is one Cm, it is one cm rainfall. To measure accurately, a measuring glass of 1/10 th base area of the rain gauge will be used. … One cm of measuring glass will then refer to one mm only and one mm will refer to 1/10th of a mm. Rainfall will therefore will be measured correct up to one-tenth of a mm.

## How fast will a rain barrel fill up?

ft. (10 ft. x 20 ft.) section of roof will fill a 60 gallon rain barrel in one day.

## 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 much rain falls on a roof?

To find how much rain you can collect in an average rain year multiply this number by the average inches of rain. For example, on a 2,000 square foot roof, you can collect 2,000 x 0.56 = 1,120 gallons/inch of rain.

## How is rain water calculated?

Simple Rainwater Harvesting Formula – For every 1” of rain and 1,000 square feet of impermeable surface (roof, driveway, etc), about 620 gallons are generated. Meaning, you can capture about . 62 gallons per sq ft. To figure out the square footage of a surface, multiply the width x length.

## How many inches of rain does it take to fill a rain barrel?

For every inch of rain that falls on a catchment area of 1,000 square feet, you can expect to collect about 600 gallons of water. So, ¼ inch of rain on an average roof = 3 full rain barrels. Ideally, you should have a rain barrel for each downspout of your home.

## Is rainwater from roof safe?

Limited studies have been conducted focusing on the safety of roof runoff for vegetable garden irrigation. … The first flush water is the initial rainwater that drains off an impervious surface, such as a driveway, parking lot, or roof and has been shown to have the highest levels of contaminants.