Cody, WY rainwater: 8,743 gallons off a roof

Rainwater from a roof in Cody, WY

8,743gallons a year

That is a 1,500 sq ft asphalt roof under Cody, WY's normal 11.0 inches of rain, about 795 gallons for every inch that falls.

In Cody, WY 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 Cody 2.4 Wsw station (2.2 mi away). Cody, WY ranks 8th wettest of the 11 cities covered in Wyoming.

Month by month in Cody

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	0.26	207
Feb	0.25	199
Mar	0.40	318
Apr	1.13	898	401
May	2.65	2,106	212
Jun	1.68	1,335	333
Jul	0.98	779	420
Aug	0.98	779	420
Sep	1.13	898	401
Oct	0.90	715	430
Nov	0.36	286
Dec	0.28	223

May is the wettest month (2.65 in, 2,106 gal off the roof); Feb the driest (0.25 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 Cody?

Best fit: 2 linked 55-gallon barrels, which delivers about 2,188 gallons to the garden in a normal year (83.6% 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 Cody's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	1,440	6,748
110 gal	2,188	5,999
165 gal	2,292	5,896
275 gal	2,292	5,896
550 gal	2,292	5,896
1,000 gal	2,292	5,896
1,500 gal	2,292	5,896
2,500 gal	2,292	5,896
5,000 gal	2,292	5,896

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 Wyoming?

No rainwater harvesting regulations

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