Barrel Composting Toilet System:
Appropriate Climates for Outdoor Installations
(Also applicable for the Bucket-to-Barrel Composting Toilet System)

(Updated 11/8/2016)


Due to the physical size of the Barrel Composting Toilet system, it is often desirable to install it in an outdoor location.  For outdoor installations, temperature requirements for composting require that the system be used where winter temperatures are warm enough to insure complete composting.  This can easily be determined by following the steps below. 

Note that the coldest outdoor locations in which the Barrel Composting Toilet system has been tested for acceptable reduction of pathogen levels (to EPA Class A Biosolids or better) have been locations with average temperatures of 50 degrees Fahrenheit or higher during the 4 coldest months.  It is possible that the system will prove suitable for colder climates, but this has not been determined at this time.

Step 1) Go to the NOAA Normals Data Access website. 

Step 2) Under "Data Access" click on "Search Tool".

Step 3) Under the "Monthly Normals" tab, click on "Arizona".

Step 4) In the column on the right, click on the proposed toilet location (or the nearest listed location having a similar elevation).

Step 5) Add up the average temperature readings for the 4 coldest months and divide the sum by 4.   

Step 6) If this figure is 50 degrees Fahrenheit or higher, the Barrel Composting Toilet system will work in an outdoor installation at that location.  If the figure is below 50 degrees Fahrenheit, add 1 barrel per person to the system for every 5 degrees lower than 50 degrees Fahrenheit.  This will ensure that compost in the aging barrels can compost fully during warmer months. 

Barrel Composting Toilet page