Superior, WI rainwater: 24,997 gallons off a roof

Superior, WI: gallons off the roof each year

24,997gallons a year

That is a 1,500 sq ft asphalt roof under Superior, WI's normal 31.5 inches of rain, about 795 gallons for every inch that falls.

In Superior, WI 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 Superior station (2.4 mi away). Superior, WI ranks 96th wettest of the 98 cities covered in Wisconsin.

Month by month in Superior

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	0.81	644
Feb	0.89	707
Mar	1.41	1,121
Apr	2.64	2,098	213
May	3.37	2,678	122
Jun	4.56	3,624
Jul	3.88	3,084	59
Aug	3.92	3,116	54
Sep	3.39	2,694	120
Oct	3.17	2,520	147
Nov	2.12	1,685
Dec	1.29	1,025

Jun is the wettest month (4.56 in, 3,624 gal off the roof); Jan the driest (0.81 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.

Which tank size is worth it in Superior

Best fit: one 55-gallon barrel, which delivers about 562 gallons to the garden in a normal year (78.7% of its need).

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

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	562	23,459
110 gal	562	23,459
165 gal	562	23,459
275 gal	562	23,459
550 gal	562	23,459
1,000 gal	562	23,459
1,500 gal	562	23,459
2,500 gal	562	23,459
5,000 gal	562	23,459

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 Wisconsin?

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