PLUMBING THE OUTDOOR URINAL
My project relates to plumbing the outdoor urinal project at the Merritt Horticulture Dept.
In this paper I will discuss the path of water and urine through the system and how the system works.
Two diagrams and several photos are included. Please note that at the time of this writing, the project
is not complete. Some of the information below may be incorrect or based on assumption, and some
aspects may need to change based on time and material constraints.
This is a rough diagram of the plumbing for the Outdoor Urinal project:
You will notice that it is a simplified system which is different than the vision initially drawn
out by Brent of Hyphae Designs for this class. The primary difference between this simplified system
and Brent's design is that the current system features no filter, whereas Brent's design includes a slow
sand filter located in the lower rain tank barrel. Here is a photo of Brent's drawing:
The decision was made to simplify the design based on difficulty finding certain parts and
questions about whether or not Brent (who has been extremely helpful) would have time to come back
to class to help us finish the system. Following the current simplified version of this system, I am
confident that we will be able to complete the project on time and test it successfully with the people
and recourses that we have at our disposal at Merritt. The other reason for eliminating the sand filter
was the question of whether or not filtration is necessary, given that the water (rainwater) is a clean
source that will be used only for hand washing and flushing a urinal. There is, however, consensus
that the sand filter is cool and would be interesting from an educational perspective to build into the
system. If we can get it together to make it all work before the end of class that would be ideal, but
this simplified nofilter design should cover us in terms of basic functionality just in case the more
elaborate design is not possible with the time that we have left. Given that this is a design without a
sand filter, I recommend posting a sign next to the sink which tells users that it is recommended not to
drink the water. I also recommend some additional signage that explains how the system works,
where the foot pump is, not to defecate into the urinal, etc.
The plumbing for this project has been superinteresting to work on and I am greatful for the
learning opportunity that it has been and for the support and efforts of class members and staff. Here's
how it works beginning with rain falling into barrels, then moving to the sink and urinal fixtures, and
flowing through drains into a constructed wetland and then down a branched drain into the landscape:
In this system, rain flows down the gutter of a specially designed butterfly roof (which
maximizes rainwater catchment) on top of the small structure that our class has constructed to house
the urinal, sink station, and rainwater tanks. After flowing down the gutter, the water lands in the first
tank which is a cutoff barrel (about 1/3 of the height of a standard 55 gallon plastic barrel) which I
will call “Barrel A”. The top 2/3 of this barrel is set aside for other use in the project. The bottom 1/3
is filled with (clean) gravel but before filling, numerous holes are drilled into in the bottom of the
barrel (using a medium sized drill bit) and a screen is stapled across the bottom of the barrel. Barrel A
provides some level of filtration to keep leaves and other debris from the roof out of the storage
tanks. Barrel A is positioned inside another barrel, which I will call “Barrel B”, which also has it's top
cut off (Seth used a sawzall for cutting barrels). Barrel B functions as a storage tank and therefore
only the top lid of the barrel has been removed. In Brent's design, a toilet float is fitted inside Barrel
B which acts as the connection between Barrel B and “Barrel C”, which is positioned below it. A
small hole is drilled into the bottom of Barrel B so that the toilet float can be fitted in place. Barrel C
is another rainwater storage tank. (In Brent's design, Barrel C houses the slow sand filter.) Given the
heaviness of water, it would be a poor design to have Barrel B full and sitting on top of Barrel C
empty, therefore we must ensure that Barrel C fills first, with Barrel B acting as the secondary storage
tank. [Note: Given that the design has changed, it is possible that the float should actually be
positioned inside Barrel C instead of Barrel B to ensure that it is Barrel C which will be our primary
resevoir. It is also possible that the toilet float (which regulates the amount of water in a given barrel)
may get eliminated from the system all together now that the sand filter has been eliminated. It is also
likely that a larger entry hole connecting Barrel B and Barrel C will be called for. The most quick and
dirty approach would probably be to remove all or most of the bottom of Barrel B, creating a singular
large resevoir or something close to it. I personally hope that we do include the float in our final
design because I think it's clever, but I have these concerns. Stability of the barrels when full should
be considered no matter what approach we ultimately take.]
Barrels A, B, and C are stacked vertically. Barrels B and C have overflows made from 1 1/2”
PVC and 90` fittings. The overflows will drain via gravity to the closest mulch basin, with the
connecting 1 1/2” PVC pipe trenched. Here is a picture of Barrels A, B, and C (without overflow
attached) in the housing built for it by the class. (Barrels B and C will also feature a 1/2” hosebib
located near the bottom of the barrels and connected with a bulkhead fitting to ensure a functional
seal. The hose bibs will allow the tanks to be easily drained for cleaning and maintenance. Note that
the hose bibs are also not attached yet in the photo below.) The last feature of the Barrels which is
also not shown in the photo below but is critical to the system is the primary supply line which
connects the outflow from barrels to the inflow to the sink. In Brent's design, this is a 1/2” hole
drilled towards the top of Barrel C, with a rubber gasket on the interior of the barrel and a male barbed
fitting sticking through, connected to a length of 1/2” flex hose, which connects to a foot pump, which
connects to the sink. Possibly there is 90` elbow connected to a piece of 1/2” pipe vertically
positioned inside Barrel C acting as a straw to ensure that the water below the output is accessible.
The foot punp (“Baby Foot” by Whale Pump) is positioned on the ground below the sink
approximately 12” from the barrels. The handles and some other components from the sink were
removed, leaving only the sink body, the spout, and the top of the drain assembly. The footpump has
2 barbed fittings, one for inflow and one for out. Flex hose connects the pump to its inflow (sourced
from the main output on Barrel C) and a second length of hose connects the pump to the sink via a
barbed fitting on the sink fixture. (We used hose clamps to ensure a good fit).
` The sink is a built into a cob counter (which is unplastered in the photo below). Drainage
for the sink consists of a drain assembly connected to a P Trap which is connected to short lengths of
1 1/2” PVC and some 90` Elbow fittings to enable the necessary turns so the drainage can be
concealed behind the cob counter. Here is a picture of the drainage for the sink:
After flowing down the sink drain the (now) greywater (used handwash water + soap) flows
through the above mentioned turns, surfaces across the interior wall of the structure, turns with a 90`
elbow to a short legth of PVC and bends down with another 90` elbow which is positioned above the
urinal structure. Water will flow freely out from this point, landing on and cleaning the urinal below
it (and hopefully not creating splash). Possibly we should use bushings to size the pipe down to
minimize splash where the greywater comes out of the system to clean the urinal.
The urinal itself will be a tire sliced in various ways to produce the shape shown below. A
drain will be positioned with a bulkhead fitting approximately where the paving stone is in the photo
below. Note that the tire curves upward in an elongated “u” shape, with the drain
positioned at its lowest point (the stone is positioned slightly too forward in this photo) and the back
of the tire mounted to the wall of the structure. Urine will travel via gravity down this same drain
before being flushed by the greywater from the sink. Here is a photo of the beginnings of the tire
urinal (notice there is no drain or mounting, etc yet).
After flowing down the sink drain the (now) greywater (used handwash water + soap) flows
through the above mentioned turns, surfaces across the interior wall of the structure, turns with a 90`
elbow to a short legth of PVC and bends down with another 90` elbow which is positioned above the
urinal structure. Water will flow freely out from this point, landing on and cleaning the urinal below
it (and hopefully not creating splash). Possibly we should use bushings to size the pipe down to
minimize splash where the greywater comes out of the system to clean the urinal.
The urinal itself will be a tire sliced in various ways to produce the shape shown below. A
drain will be positioned with a bulkhead fitting approximately where the paving stone is in the photo
below. Note that the tire curves upward in an elongated asemetrical “u” shape, with the drain
positioned at its lowest point (the stone is positioned slightly too forward in this photo) and the back
of the tire mounted to the wall of the structure. Urine will travel via gravity down this same drain
before being flushed by the greywater from the sink. Here is a photo of the beginnings of the tire
urinal (notice there is no drain or mounting, etc yet).
As a final step, we may dig a trench to be filled with gravel at the bottom of the hill in case the flow is too
great for the infrastructure above. However, it is likely that the issue for the system will be that the flow is too
flow, not too high, as it is anticipated that most of the year the urinal will receive only light use. Again, it has
been an excellent experience for me to work on this project. I thank Marisha, Brent, Molly, and Anders, as
well as classmates Seth, Jordan, Nathan, Morgan, Kendra, and others.
