Rain catchment experts

[ken800]

I would do it in inches since that's how they measure rainfall but that's just me.

Measure your roof dimensions. You want the area that is facing upward. An extreme angle won't catch as much as perfectly flat. Imagine a vertical sheet of metal. It will catch little assuming rain falls vertically. Use the Pythagorean theorem to figure out the base of your right triangle and you'll know your effective area assuming, again, the rain falls vertically.

There are 231 cubic inches in a gallon. So lets say your roof is 10'x10' for 120"x120" and is FLAT. Your surface area is 14,400 square inches. If you got 1/4" of rain and captured every drop on the roof, you'd have 1/4x14,400= 3600 cubic inches of water divided by 231 or 15.6 gallons of water.

Those little 4x4 roof catchment systems I've seen would then pull 48*48*rainfall / 231. Assuming a 1" rainstorm which is a lot, lol, you'd get about 10 gallons of water which ain't much.

Move that up to 1" on the 10x10 and you get 14400/231 or 62 gallons.

Look at your average rainfall in your area and you'll know about how much water you can harvest before you spend your money...

Go big or go home.

[lilbradford]

I would do it in inches since that's how they measure rainfall but that's just me.

Measure your roof dimensions. You want the area that is facing upward. An extreme angle won't catch as much as perfectly flat. Imagine a vertical sheet of metal. It will catch little assuming rain falls vertically. Use the Pythagorean theorem to figure out the base of your right triangle and you'll know your effective area assuming, again, the rain falls vertically.

There are 231 cubic inches in a gallon. So lets say your roof is 10'x10' for 120"x120" and is FLAT. Your surface area is 14,400 square inches. If you got 1/4" of rain and captured every drop on the roof, you'd have 1/4x14,400= 3600 cubic inches of water divided by 231 or 15.6 gallons of water.

Those little 4x4 roof catchment systems I've seen would then pull 48*48*rainfall / 231. Assuming a 1" rainstorm which is a lot, lol, you'd get about 10 gallons of water which ain't much.

Move that up to 1" on the 10x10 and you get 14400/231 or 62 gallons.

Look at your average rainfall in your area and you'll know about how much water you can harvest before you spend your money...

Go big or go home.

Good advice right here ^^ especially that last part

[SFAbowhunter]

I would do it in inches since that's how they measure rainfall but that's just me.

Measure your roof dimensions. You want the area that is facing upward. An extreme angle won't catch as much as perfectly flat. Imagine a vertical sheet of metal. It will catch little assuming rain falls vertically. Use the Pythagorean theorem to figure out the base of your right triangle and you'll know your effective area assuming, again, the rain falls vertically.

There are 231 cubic inches in a gallon. So lets say your roof is 10'x10' for 120"x120" and is FLAT. Your surface area is 14,400 square inches. If you got 1/4" of rain and captured every drop on the roof, you'd have 1/4x14,400= 3600 cubic inches of water divided by 231 or 15.6 gallons of water.

Those little 4x4 roof catchment systems I've seen would then pull 48*48*rainfall / 231. Assuming a 1" rainstorm which is a lot, lol, you'd get about 10 gallons of water which ain't much.

Move that up to 1" on the 10x10 and you get 14400/231 or 62 gallons.

Look at your average rainfall in your area and you'll know about how much water you can harvest before you spend your money...

Go big or go home.

Great info!

I have been looking at ways to get water on my place in SE Oklahoma without having to dig a well. As of today I have gotten 21" of rain since Jan. 1 at my place. I believe I average around 60-70" of rain a year, so I could collect over 3,700 gallons of water with a 10x10 roof over a full year. That ain't too bad! Might have to give this more thought! Could probably save some money going this route vs the well.

[HoustonR6ryda]

please post pics of progress-good luck

[ken800]

Great info!

I have been looking at ways to get water on my place in SE Oklahoma without having to dig a well. As of today I have gotten 21" of rain since Jan. 1 at my place. I believe I average around 60-70" of rain a year, so I could collect over 3,700 gallons of water with a 10x10 roof over a full year. That ain't too bad! Might have to give this more thought! Could probably save some money going this route vs the well.

Well... If you get that much rain, lol, make sure you get a big enough tank to hold it all. Add a solar-powered pump and you are golden. I've got a 2500 gallon enduraplas.

IF you end up doing this, consider the fact that your time will be the biggest thing you invest. Consider cost of 10x10 sheet metal. Add 50% more and you are maybe a hundred bucks more. Better to over than under. At some point, I'll probably build a cover for a travel trailer at my place in Lampasas and it will double duty as water catchment. figure 36x12 or so and even with 33 inches of rain per year, would be 9K or so gallons of water. Occasional bleach, a good filtration system, and you are good to go.

[joel45acp]

I’m reconsidering using my cabins roof (16x30) as the catchment system instead of building 2 small 40sq ft catchment systems. Lots to plan at this point.

[SFAbowhunter]

Well... If you get that much rain, lol, make sure you get a big enough tank to hold it all. Add a solar-powered pump and you are golden. I've got a 2500 gallon enduraplas.

IF you end up doing this, consider the fact that your time will be the biggest thing you invest. Consider cost of 10x10 sheet metal. Add 50% more and you are maybe a hundred bucks more. Better to over than under. At some point, I'll probably build a cover for a travel trailer at my place in Lampasas and it will double duty as water catchment. figure 36x12 or so and even with 33 inches of rain per year, would be 9K or so gallons of water. Occasional bleach, a good filtration system, and you are good to go.

Thanks! When I add a travel trailer to my place I'll build a cover for it and use it to collect the water. Sounds like this may be cheaper than digging a well. We'll see!

[PassnItOn]

Great thread, I'm doubling my capacity now and hope to get about 21,000 gallons a year (using whole house) - do you guys add any treatment to the water in the tank?

[joel45acp]

Great thread, I'm doubling my capacity now and hope to get about 21,000 gallons a year (using whole house) - do you guys add any treatment to the water in the tank?

I’ll be adding a pool chorine tablet to the tanks every so often.