Gurnee, IL rainwater: 28,939 gallons off a roof

Rainwater from a roof in Gurnee, IL

In Gurnee, IL 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 Gurnee Public Works station (0.9 mi away). Gurnee, IL ranks 216th wettest of the 225 cities covered in Illinois.

Month by month in Gurnee

Jun is the wettest month (4.09 in, 3,251 gal off the roof); Dec the driest (1.87 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 Gurnee?

Best fit: one 55-gallon barrel, which delivers about 487 gallons to the garden in a normal year (81.4% 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 Gurnee's roof water will pass straight through it.

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 Illinois?

Local government can regulate rainwater harvesting per state plumbing law

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