100'x100'x52" = how many gallons?

[pjharvey]

Ok, I am trying to determine how many gallons of water will be required annually to water my lawn.

Given an area of 1,000 square feet
Given 1 inch of water added per week
Given a 52 week period
Given 1 cubic foot = 7.48 gallons (right?)

So, if I were to put 52 inches of water into a 1,000 square foot area how many gallons is that?

I did this (7,480 x 52) / 12 = 32,413 gallons

Not real confident this is correct.. so any help would be appreciated!

[Guest]

Ok, I am trying to determine how many gallons of water will be required annually to water my lawn.

Given an area of 1,000 square feet
Given 1 inch of water added per week
Given a 52 week period
Given 1 cubic foot = 7.48 gallons (right?)

So, if I were to put 52 inches of water into a 1,000 square foot area how many gallons is that?

I did this (7,480 x 52) / 12 = 32,413 gallons

The calculation is correct assuming you need 52" of watering per year.

But it may depemd on where you are. In northern states, we don't water in winter. Also, some weeks there is enough rain to water naturally. It really depends on conditions. It might easily reduce to half or one quarter that amount. In a warm desert, your calculation may be the answer.

Not real confident this is correct.. so any help would be appreciated!

[Guest]

The calculation is correct assuming you need 52" of watering per year.

But it may depemd on where you are. In northern states, we don't water in winter. Also, some weeks there is enough rain to water naturally. It really depends on conditions. It might easily reduce to half or one quarter that amount. In a warm desert, your calculation may be the answer.

True, I will likely need 2" per week in the summer and near zero in the winter. Was just trying to get an idea what my non-domestic usage might be given a general approximation.

Thank you for verifying my calculation.

[sxyntx]

The only flaw I found is that that a cubic foot of water is 12x12x12.........so it's actually 12 inches of water added......

to water 1 square foot 1" is .65 gallons (7.8/12)

hope that helps!

[sxyntx]

NEVERMIND!!!!

I see what you did.......you divided everything by 12 which achieves the same thing.

That is assuming you get NO rainfall in a year and works out to be 620 gallons per week needed to achieve that 1"!

I live in Texas........and we get an average of 31" of rainfall per year. Depending on how it comes, that's about 31 weeks I don't have to water my grass (have about the same size yard). I rarely have to water November - February. That's 16 weeks where I might water 3-5 times. March, April and October I may water every other week so that is 6. May, June, July, August and September I will water on average 1 time a week (the reality being some weeks I don't have to and other weeks water 2x) so that is 20.

On average, I will have to water 31 inches throughout the year..........at 650 gallons per inch to water a 1000 sf yard space..........I need 650,000 gallons of water over a year.

Geez....when you put it that way, no wonder my yard is brown and my water bill is OFF THE CHART!!!!!

Now, I'm really needing a rainwater harvesting system.........and this will help me justify the cost (as well as save my yard)!!!!!