How Much Roof Space For Water Collection

Doesn t that sound like a lot of water that you could harvest and use for free.

How much roof space for water collection. Calculating your harvestable rainwater. 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.

Rainwater collection calculator in gallons. 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. Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water. The resulting number represents how many litres of water you can expect to collect.

There are many benefits to installing a rainwater collection system and collecting rainwater for your home and these benefits apply to all kinds of rainwater systems. 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. If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year.

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. A typical water conserving house will use 25 to 50 gallons of water per day when averaged across all members of the household. To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above. For example on a 2 000 square foot roof you can collect 2 000 x 0 56 1 120 gallons inch of rain.

The resulting figure represents the surface area of your roof in square metres. That is why my husband and i began harvesting our rainwater. Annual rainfall in millimetres x roof surface area in square metres roof catchment capacity. Around 600 gallons of rainwater can be harvested from about one inch of rain if it falls from a thousand square foot roof.

Well we thought so too. To work out the surface area simply multiply the length in metres by width for. This capacity can be calculated using the following formula.