Mexico, MO rainwater: 34,590 gallons off a roof

Rainwater from a roof in Mexico, MO

In Mexico, MO 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 Mexico station (1.2 mi away). Mexico, MO ranks 48th wettest of the 80 cities covered in Missouri.

Month by month in Mexico

Jun is the wettest month (5.23 in, 4,157 gal off the roof); Jan the driest (2.03 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 Mexico

Best fit: one 55-gallon barrel, which delivers about 202 gallons to the garden in a normal year (81.4% 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 Mexico'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 Missouri?

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