Barrel Composting Toilet System:
Urine Diversion System

(Updated 5/14/2016)


2016 Update:

In photos and description below, note change in urine diverter orientation for improved user interface.  

Urine separation is an integral component of the Barrel Composting Toilet System.  The recommended system for urine diversion is described below.  The system consists of 3 basic assemblies: a urine diverter built into each barrel, a subsurface leaching chamber for each barrel and an optional urinal for men.  Perennial plants located near the leaching chambers are recommended for utilizing water and nitrogen in the urine. 

For information on the sizing of the bucket leaching chamber, see Barrel Composting Toilet System: Capacity Calculations and System Sizing

Urine diverter in barrel toilet.  A urine diverter for each barrel is recommended.  This is more convenient than moving a single diverter from one barrel to the next. 

Note: Either the tall side or the short side of the funnel can be mounted toward the front of the barrel.  For best user interface, we now recommend mounting the tall side toward the front of the barrel. 

Stainless steel screen to prevent urine drain from clogging.  Urine drain is made from Super Quick Fill Funnel and secured to barrel with two #10 x 2" stainless steel machine screws and nuts. 




Urine diverter secured to front of barrel with stainless steel machine screws.  Note urine drain hose at bottom of funnel.

Note: Either the tall side or the short side of the funnel can be mounted toward the front of the barrel.  For best user interface, we now recommend mounting the tall side toward the front of the barrel (as shown above).

Urine diverter construction begins with drilling 1/2" hole vertically through rubber stopper.  During drilling, grip stopper gently but firmly with pliers.


Pass hose through funnel, then slide stopper onto hose until end of hose is flush with top of stopper. 

Urine diverter ready to mount.  Stopper and hose assembly is pressed into bottom of funnel. Note stopper extending from bottom of funnel.

Note: Either the tall side or the short side of the funnel can be mounted toward the front of the barrel.  For best user interface, we now recommend mounting the tall side toward the front of the barrel (opposite of what is shown in above photo).

Drill two 3/16" diameter holes in front of barrel for mounting diverter.  Holes should be centered on front of barrel and located 2" and 3" below the bottom side of the lip at the top of the barrel.     

Leaching chamber made from bottom half of 5 gallon bucket.  1/2" diameter holes are drilled through side of bucket near top.

Leaching chamber is buried so top is several inches below grade.  One chamber is required for each barrel in the system.  Note 2-1/2" diameter hole drilled into top of chamber.  This allows future inspection of chamber. 

 Each leaching chamber should be located within 12" of the barrel it's connected to.  This keeps drain hose as short as possible.  Note: Drain hoses must be level or preferably downhill throughout their entire length.  Uphill sections, even short ones, will tend to stop urine from flowing. 

4" PVC plumbing cap covers hole on chamber top.  Note urine drain hose exiting front of barrel.  Also note 1/2" plastic cable clamps and 1/2" stainless steel machine screws securing drain hose.  

Men's urinal made from FloTool Giant funnel.  Stopper is same as used in making urine diverter.  Note that urinal is clearly marked for visitors.

Top view of urinal showing rubber stopper/drain hose in bottom of funnel.  Drain hose for urinal can be plumbed into leaching chamber for toilet if urinal is within 5-6' of leaching chamber.   Otherwise, plumb hose into separate leaching chamber.     

Handwashing bucket and urinal mounted on pipe.  Note that bucket and urinal are clearly marked for visitors.

Notes on construction:

--#10 stainless steel fasteners are used for securing the urine diverter to the barrel, for securing the urine drain cable clamps to the barrel and for securing the men's urinal to whatever surface it's mounted on.  Holes for these fasteners should be drilled using a 3/16" diameter drill bit.  

--The two holes for mounting the urine diverter to the barrel should be centered on the front of the barrel, about 2" and 3" below the lip at the top of the barrel (see photo above).  Inserting the urine diverter fasteners through these holes is easier if the holes are a bit larger than 3/16" diameter (7/32" is good)     

--The hole for the urine drain hose to exit the barrel should be 1/2" in diameter and centered on the front of the barrel, about 12" below the top of the barrel.  

--The urine drain hose from each barrel will go into a hole drilled near the top of the leaching chamber.  Both of these 2 holes should be 1/2" diameter. 

--Take care to be sure that hoses are level or downhill all the way from urine diversion funnels to leaching chamber.  If not, air bubbles may form in uphill sections, preventing urine from flowing. 

--Insert the hose into the funnel (this applies to both the urinal funnel and the diverter funnel), then press the hose into the rubber stopper.  Use soapy water on the end of the hose and on the rubber stopper to help get the hose into the stopper.  Gently press the stopper down into the funnel for a liquid-tight seal. 


Notes on use:

--The urine diversion system so effectively keeps urine out of the toilet barrel that some urine or water may have to be poured back into the barrel periodically to maintain sufficient moisture for effective decomposition.  

--Occasionally pieces of cover material may fall into the urine diverter.  If so, remove the screen from the diverter, turn it upside down and spray it clean with squirt bottle used for wetting toilet paper.  

--Check bottom of diverter occasionally to be sure rubber stopper around urine drain hose is snug.  A loose stopper can allow excessive amounts of urine to enter the active barrel, causing anaerobic conditions and resulting odors.  


--See the "Troubleshooting" section of the Barrel Composting Toilet System: Owner's Manual



Materials List for Urine Diversion System

 Urine Diverter (per barrel):

--Funnel, FloTool Super Quick Fill #10714WR                                                 $4.00 (AutoZone)
--Fuel line, 1/4” I.D. 8'@$1.20/ft.                                                                         $9.00 (AutoZone)
--Rubber stopper, 1" top dia., 3/4" bottom dia., 1" high                                   $1.00 (Ace)
--Cable clamps, 1/2” plastic, 3@$.20                                                                $1.00 (Ace)
--Machine screws, stainless steel, pan-head #10-24 X 2”  2@$.40              $1.00 (Ace)
–Flat washers, stainless steel, #10  4@$.20                                                    $1.00 (Ace)
--Nuts, stainless steel, #10-24  11@$.15                                                          $2.00 (Ace)
--Machine screws, stainless steel, pan-head #10-24 X 1/2”  3@$.20           $1.00 (Ace)
--Sink screen, Danco # 88822                                                                           $4.00 (Home Depot)


 Men's Urinal:

--Funnel, FloTool Giant  # 10705                                                                     $5.00 (AutoZone)
--Fuel line, 1/4” I.D., 1/2" O.D.   4'@$1.20/ft.                                                  $5.00 (AutoZone)
--Rubber stopper, 1" top dia., 3/4" bottom dia., 1" high                                $1.00 (Ace)
–-Cable clamps, 1/2” plastic, 3@$.20                                                            $1.00 (Ace)

 Leaching Chamber (per barrel):

--5 gallon plastic bucket, 1 @ $4.00                                                                $4.00 (Hardware Store)
                                                                                                            Total         $40.00