Diverting Urine in a Compost Toilet System

Tuesday, 28th April 2015

A how-to guide to building a barrel composting system with a urine diverter.

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 two basic assemblies: a urine diverter built into each barrel and a hose to transport urine to an approved drainage system.

For outdoor installations, check with your local regulator to see if the subsurface leaching chamber system described below may be approved. One leaching chamber is required for each barrel. Also described below is an optional urinal for men. Perennial plants located near the leaching chambers are recommended for uptake of water and nitrogen in the urine.

For information on the sizing of the bucket leaching chamber, see Barrel Composting Toilet System: Calculating Effective Leaching Chamber Sizing for Subsurface Disposal of Urine

The diverter is made from a Super Quick Fill funnel available at auto parts stores. The drain hose is 1/4inc (6.4mm) fuel line. The reason for the small diameter hose is that urine is high in dissolved minerals that will precipitate over time on the inside of drain pipes. Rinsing the urine diverter after each use requires only 1/4-1/2 cup of water to thoroughly clean the entire inside surface of the hose, thus preventing mineral formation. A stainless steel screen prevents clogging of the hose. Also, in the unlikely event that clogging occurs, a plumbing 'snake' can be inexpensively constructed as described in the 'Troubleshooting' section of the Barrel Composting Toilet System: Owner's Manual.

Another advantage of the small diameter hose is that it prevents insects from entering the toilet from the leaching chamber via the hose.


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.


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 2inc (5cm) 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.


Urine diverter construction begins with drilling 1/2inc (1.2cm) hole vertically through rubber stopper. During frilling, grip stopper gently but firmly with pliers.


Drill two 3/16inc diameter holes in front of barrel for mounting diverter. Holes should be centered on front of barrel and located 2inc (5cm) and 3inc (7.6cm) below the bottom side of the lip at the top of the barrel.


Leaching chamber made from bottom half of 5 gallon bucket. 1/2inc (1.2cm) diameter holes are drilled through side of bucket near top. One hole is required for each hose.


Leaching chamber is buried so top is several inches below grade. One chamber is required for each barrel in the system. Note 2.5inc (6.3cm) diameter hole drilled into top of chamber. This allows future inspection of chamber.


Each leaching chamber should be located within 12inc (30.4cm) 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.


4inc (10.1cm) PVC plumbing cap covers hole on chamber top. Note urine drain hose exiting front of barrel. Also note 1/2inc (1.2cm) plastic cable clamps and 1/2inc 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 3/16inc diameter drill bit.

– The two holes for mounting the urine diverter to the barrel should be centered on the front of the barrel, about 2inc and 3inc 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 3/16inc diameter (7/32inc is good)

– The hole for the urine drain hose to exit the barrel should be 1/2inc in diameter and centered on the front of the barrel, about 12inc 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 1/2inc 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

– After each use of the urine diverter or men's urinal, rinse the inside with a couple squirts of water from the water bottle located by the toilet.

– 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

Originally appeared www.omick.net/composting_toilets/barrel_toilet_urine_diversion.htm Visit to find out the cost prices for the parts.

Further resources

Recycling human waste to improve sanitation and produce food

How to make a vermicomposting flush toilet

Liquid Gold - The Lore and Logic of Using Urine to Grow Plants


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John Waters |
Sun, 03/05/2015 - 01:29

Urine is a very valuable source of nutrients. In particular phoshate and many others. I believe in one of the Scandinavian countries, urine is collected from public toilets and treated then used as a garden fertilizer.