How can I figure out how much water comes off my roof when it rains?

Question

How can I figure out how much water comes off my roof when it rains?

Answer 1

They have some measuring devices at the store.  Look into one of those and see if it'll help you.

Our roof is slanted and we don't have a gutter to catch the rain.  One of our monsoon storms hit the other day and filled up my garbage can (which was nearly empty) about 2/3rds of the way.  I don't know how to figure that out... BUT! That's an awful lot of water being wasted.... 'cause the landlord was too cheap to install gutters and a barrel to catch the rain.  

Answer 2

On way is to place a bucket at the outlet of the downspout if you have one.

Or, position one of those rubber utility containers that measure about 2 ft. X 3 ft. that you can buy at Walmart and find a convenient place to put it where you have a downspout. You'll need to measure it at the downspout since that's the collection point for the water running off the roof.

There are rain gauges you can buy that just measure rain as it falls, not necessarily coming off the roof.

Answer 3

put a barrel under your leader pipe

Answer 4

Measure the square footage covered by the roof. Do not figure the total square footage of the roof just the square footage of the area under the roof. The formula is 1 Sq. Ft. = .623 gallons for each inch of rain. In other words a 1000 square foot coverage would provide 623 gallons with one inch of rain.