Coweta, OK rainwater: 34,383 gallons off a roof

How much rain a roof in Coweta, OK collects

34,383gallons a year

That is a 1,500 sq ft asphalt roof under Coweta, OK's normal 43.3 inches of rain, about 795 gallons for every inch that falls.

In Coweta, OK a single barrel does most of the work. Storms come often enough that a small tank refills before it runs dry, and a bigger one would mostly sit full.

Rainfall: NOAA 1991-2020 climate normals, the Broken Arrow 2.2 Sw station (8.8 mi away). Coweta, OK ranks 10th wettest of the 45 cities covered in Oklahoma.

Month by month in Coweta

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	1.83	1,454
Feb	1.87	1,486
Mar	3.43	2,726
Apr	4.47	3,553
May	6.30	5,007
Jun	4.80	3,815
Jul	3.84	3,052	64
Aug	3.72	2,957	79
Sep	3.97	3,155	47
Oct	3.83	3,044	65
Nov	2.66	2,114
Dec	2.54	2,019

May is the wettest month (6.30 in, 5,007 gal off the roof); Jan the driest (1.83 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.

Barrel or cistern in Coweta?

Best fit: one 55-gallon barrel, which delivers about 214 gallons to the garden in a normal year (84.1% of its need).

If you set one up, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Coweta's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	214	33,239
110 gal	214	33,239
165 gal	214	33,239
275 gal	214	33,239
550 gal	214	33,239
1,000 gal	214	33,239
1,500 gal	214	33,239
2,500 gal	214	33,239
5,000 gal	214	33,239

Simulated storm by storm through a normal year using the station's count of days with 0.1 in or more of rain each month.

Is rainwater collection legal in Oklahoma?

Encouraged through state legislation: Water for 2060 Act

From the 2015 (Pacific Northwest National Laboratory report 24347); not yet re-checked against current law, so check with your state water agency before building anything large. Source