How Much Roof Space For Water Collection

To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.

How much roof space for water collection.

Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year. Annual rainfall in millimetres x roof surface area in square metres roof catchment capacity. The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.

Calculating your catchment capacity roughly speaking 1 millimetre of rain over 1 square metre of roof equals 1 litre of water. Since rainwater is collected from rooftops you will need to work out the total surface area of roof s that will be used to catch rainwater. To calculate how much rainwater can be harvested multiply your rainfall mm by your roof surface area m 2 being used to catch rainwater. In order to determine how much water you should collect with your roof mounted rainwater collection system you need to figure your estimated usage or demand.

The first and most obvious benefit is that rainwater is free so having a collection system lets you gather your own source of free water. The resulting figure represents the surface area of your roof in square metres. The resulting number represents how many litres of water you can expect to collect. Rainwater collection calculator in gallons.

Around 600 gallons of rainwater can be harvested from about one inch of rain if it falls from a thousand square foot roof. Let s take a look at one more example to see how much of a difference collecting rainwater can make if you live in boston massachusetts which gets an average of 42 53 inches of rain per year and you live in a house with 1 000 square feet of roof space 1 000 x 0 6 x 42 53 25 518 gallons of water collected each year in boston ma. A typical water conserving house will use 25 to 50 gallons of water per day when averaged across all members of the household. Well we thought so too.

When you look at the numbers it s surprising how much water you can collect every time it rains. Doesn t that sound like a lot of water that you could harvest and use for free. One quick way to ballpark estimated usage is to look at old utility bill and divide that number by the number of individuals in your household. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain.

To work out the surface area simply multiply the length in metres by width for. This capacity can be calculated using the following formula. Rainwater can be collected from the roofs using the rain water harvesting method.