Enid, OK rainwater: 26,459 gallons off a roof

Enid, OK: gallons off the roof each year

26,459gallons a year

That is a 1,500 sq ft asphalt roof under Enid, OK's normal 33.3 inches of rain, about 795 gallons for every inch that falls.

In Enid, 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 Enid station (0.9 mi away). Enid, OK ranks 38th wettest of the 45 cities covered in Oklahoma.

Month by month in Enid

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	1.04	827
Feb	1.28	1,017
Mar	2.41	1,915
Apr	3.42	2,718	116
May	4.36	3,465
Jun	4.83	3,839
Jul	3.34	2,655	126
Aug	3.63	2,885	90
Sep	2.73	2,170	202
Oct	3.06	2,432	161
Nov	1.69	1,343
Dec	1.50	1,192

Jun is the wettest month (4.83 in, 3,839 gal off the roof); Jan the driest (1.04 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.

What size rain barrel for Enid

Best fit: one 55-gallon barrel, which delivers about 593 gallons to the garden in a normal year (85.4% of its need).

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

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	593	25,131
110 gal	593	25,131
165 gal	593	25,131
275 gal	593	25,131
550 gal	593	25,131
1,000 gal	593	25,131
1,500 gal	593	25,131
2,500 gal	593	25,131
5,000 gal	593	25,131

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