Waunakee, WI rainwater: 29,511 gallons off a roof

Waunakee, WI: gallons off the roof each year

29,511gallons a year

That is a 1,500 sq ft asphalt roof under Waunakee, WI's normal 37.1 inches of rain, about 795 gallons for every inch that falls.

In Waunakee, 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 Madison Dane Rgnl Ap station (5.8 mi away). Waunakee, WI ranks 22nd wettest of the 98 cities covered in Wisconsin.

Month by month in Waunakee

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	1.47	1,168
Feb	1.52	1,208
Mar	2.26	1,796
Apr	3.78	3,004	71
May	4.10	3,259	31
Jun	5.28	4,197
Jul	4.51	3,585
Aug	4.16	3,306	24
Sep	3.43	2,726	115
Oct	2.77	2,202	197
Nov	2.22	1,764
Dec	1.63	1,296

Jun is the wettest month (5.28 in, 4,197 gal off the roof); Jan the driest (1.47 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 Waunakee

Best fit: one 55-gallon barrel, which delivers about 346 gallons to the garden in a normal year (79.1% 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 Waunakee's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	346	28,100
110 gal	346	28,100
165 gal	346	28,100
275 gal	346	28,100
550 gal	346	28,100
1,000 gal	346	28,100
1,500 gal	346	28,100
2,500 gal	346	28,100
5,000 gal	346	28,100

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