Don't Linger Too Long in the Outhouse . . . .
Building Principles

by Rick Stryker, P.E.

Don't linger too long in the outhouse,
For there's creatures that live in the hole.
When you're work there is done,
Pull your pants up and run,
If you want to be savin' your soul.
Source: www.wavlist.com/holidays/002/index.html

Would you believe that this was the only song I could find about outhouses? If this isn't a camp song already, it should be an instant classic now.

"Primitive" toilets or "privies," are pretty rare outside the camp community, so you might think that there's nothing new under the sun. In large measure, that's true. Because they're inevitably constructed identically to their predecessors, the new outhouses are as unappealing as the old ones that they replaced. Could it be a self-fulfilling prophecy through repetition? I have great news that there is, indeed, a better way to build this mousetrap!

The key here is acknowledging that although there are several overall complaints about them, there are two primary objections to outhouses: Odor and visibility of waste. Put simply, these are aesthetic issues which are not all that hard to overcome with a basic understanding of the source of the odor and considerable attention to detail in design and construction. Ideally, the features we're going to discuss this month would be incorporated into a new facility. But the ideas and principles which follow can be incorporated into existing units. The more features you can add, the better chance you stand of breaking the cycle. Let's look specifically at what causes the most offensive odors, and how the selection of materials and careful geometry/design can help reduce the odor problem, perhaps eliminating it altogether.

Let's look at the simpler issue first. There's no easy way to say it: Opening the lid to a pit toilet seat in preparation for use is no visual treat. But in an effort to better light this space, there's inevitably a skylight overhead which, regardless of the time of day, seems to send a spotlight directly onto the contents below. There are two features that lessen this effect. Most importantly, stop putting skylights in the roof! Instead, install short, clear Lexan panels in the side walls near the top for light. Next, a vault should have about 18" – 24" of sanitizing liquid in the bottom. The vault floor should slope toward the exterior clean out, to allow gravity to work for you. There! We've solved the visual hang-ups!

The much more complex issue, and frankly the bigger stumbling block, is odor. To solve this will require an understanding of waste odor and its sources. Then common sense will dictate many of the features and improvements which will help.

Primitive Waste Receptacles

To begin, we need to understand that there are actually two different primitive waste receptacles that may look the same, but which are very different in operation and level of service. A "pit" toilet is simply that: Waste is collected in a hole or pit contained below the ground directly under the seat of the privy. It is not sealed, and water moves freely into and out of the pit (hopefully always underground!). By the time that the pit is filled, the structure above is normally shot, so the building is demolished, the hole is filled and covered and a new location is dug. A vault configuration on the other hand, collects waste in a sub-surface structure designed to contain and hold waste inside until it is pumped clear (usually at the end of the season). Though it's intended to hold 18" – 24" of water, groundwater should never enter or leave the structure. Your system probably began as either of these and has morphed into a cross between these two over time. If you have a privy with characteristics of both types, the system is probably not functioning correctly. Major maintenance, repair, or outright replacement is in the very near future.

Without question, the biggest complaint about primitive facilities is foul odor. Properly functioning, an "earthy rotten egg" smell is common at privies when waste digestion is in full swing. This odor is a normal part of waste decomposition. But an overwhelming stench isn't necessarily something that you have to live with. Understand that the decomposition process is actually a progression of largely sequential processes by which microbes consume the waste and oxygen from the air and in turn release more noxious compounds like hydrogen sulfide (aerobic digestion). After a while though, essentially all of the available oxygen has been consumed and new, (even stinkier!) microbes take over. These anaerobes consume remaining nutrients in the waste without using air in the process. This different is the source of the "Oh my goodness! What died in THERE?" smell. Had the first batch of microbes been supplied with fresh air all along, they would have continued making their earthy odors for weeks and months. So what's the key here? Obviously, we need to keep the space around the waste well ventilated and fresh air exchanging all the time. We'll get back to how to do that in a bit.

What can we do about any smell in the building? Enter ventilation again! If we can create a condition where air moves from outside, through the people compartment, into the waste compartment and then out of the structure altogether, then the air in the building will always be fresh, and the foul air will be, well, elsewhere. This is what we were after anyway, right?

Proper Ventilation

So how do we set that air flow up? Begin by forgetting everything that you ever thought that you knew about outhouse architecture. In its simplest terms, we're trying to set up a one-way flow of air: one path for air to move through the building and then out. This means that screens at the top, spaces at the bottom, and moons in the door all have to go. The building itself has to be largely air tight with a single vent placed, head-high in the upwind side of the building. Another counter-intuitive and unconventional feature of the system is that the toilet lids must not seal to the seat. We're trying to provide a single path for air to flow through the building, past the waste and out the vent and the seat/riser is the route that we're after. You want air moving through the building all the time. Remember: In through the vent, down through the seat riser, past the waste beneath, and out through the vent stack.

Next, use the sun to help move air through the unit by convection. Start by painting the vent stack black. This will make the stack less noticeable, but more importantly, the color will help to hold the radiant heat from the sun, creating a convective air current rising in the stack. Moving air here will pull air through the vent in the building, and you'll have circulation on the most windless days. In fact, the hotter and more still the day, the breezier that the building will feel! Geometrically, make sure that the stack itself rises at least 3' above the height of the roof. This helps to reduce flow turbulence near the roof and makes the most out of any breeze that's blowing. Finally, don't cover the stack, attach a chimney cover, install screen, or otherwise obstruct air flow.

Keep in mind that odorous gasses are still being produced, but they're being vented outside all the time, in relatively low concentrations, making the effects on folks downwind much, much less noticeable and offensive. But the odor will be from the much less offensive aerobes instead of those really funky anaerobes. Yes. It's likely to be warm inside the building with a single screened 10" x 12" vent. But generally speaking, people are much more tolerant of a "too warm" place to go than they are a "too smelly" place to go.

Better Design

We promised that we'd talk about design features that will help make your outhouse less offensive. Here are just a few that should get you started. You should note that certain themes have been repeated for emphasis…

1. Correct venting.
2. Probably the most important feature to consider inside the building is that the materials you use for primitive facilities need to be as nonporous as you can possibly afford. Painted wood is better than bare wood, but with time and changes in humidity, it will warp, crack and peel.
3. Contrary to popular belief, concrete is very porous! For it to not become a giant Petri dish of funky bacteria, you must seal the surface with a penetrating sealant. Don't use tar-based sealants because although they do, indeed, seal the concrete, the coatings themselves become the breeding ground you're trying to avoid. Consider CIM 1000 (www.cimind.com) or EverCrete (www.evercrete.com/dps_info.html). Both products seal the concrete and can be painted with an enamel coating for a more pleasing final finish (check the manufacturer's recommendations).
4. A single path of air flow: Venting.
5. Consider covering interior surfaces with stainless steel or fiberglass panels. Any easily cleaned, non-porous surface will go a long way toward reducing outhouse odor.
6. If you install a urinal, make sure that the drain pipe extends all the way into the liquid below. This will create a water seal and prevent the urinal from becoming another air flow path. Did I mention venting before?
7. If the building itself is unshaded, add insulation to the roof. If the inside of the building becomes as warm as the air in the vent stack, the air won't circulate properly.
8. Consider how the spaces will be cleaned when they're done being built. No surface should hold water or moisture either from wind-driven rain or residual cleaning chemicals or wash down.
9. And then there's correct venting.
10. Avoid inside right angle crevices by using ogee molding or a generous application of silicone caulk, smoothed and pressed into the joint with a wet finger tip.
11. Make sure that the floor in the building is sloped toward the door and that there are no places for water to puddle or debris to accumulate.
12. Install a proper, large volume, tamperresistant paper dispenser. This is as much a customer service feature as it is an operational one, since there are few indignities or frustrations as those associated with no supplies.
13. Provide a 2' diameter access outside the building, otherwise the waste has to be removed through the seat and riser. By its nature, this is neither a neat nor pleasant task and requires considerable banging around and splashing. You really, really want to keep that outside the building, and by providing a full size access to the vault outside in broad daylight, the pumper has no excuse for not being thorough in his service call.
14. If you need a multiple-seat facility, make sure that each seat has its own path for air flow. This will require some creative framing above ground, and probably baffling of the chambers below. But if you want the ventilation scheme to work, you'll need to think outside of the [proverbial] box.

Care and maintenance — Once the "whys" of odor generation are understood and you've done what you can to abate them by ventilation and by material selection, you're left to care for the facility. If not "inviting," at least the space won't be outright revolting. There's no reason remaining not to give all of the surfaces all of the disinfectant, care, and attention to detail that they can handle. The nooks, crannies and crevices that couldn't be avoided in the design and construction must be cleaned and disinfected completely and regularly if the space is to remain as odor free and sanitary as possible.

The next aspect is pumping. If old waste is the smelliest, then years-old waste is exponentially the worst. Pit privies weren't intended to be pumped clear of waste, only abandoned, so if you call for it to be pumped, the honey-dip truck driver can only extract the waste through the riser and seat area. If the job is complete and thorough, splashing is inevitable. Major disinfection and wash-down must follow. Though the issues are similar for a properly constructed vault system, post-pumping recovery is obviously much simpler outside. Have the vault pumped in the autumn.

Privies are a necessity for many organizations with remote program elements or limited water supply and sewage disposal infrastructure. Properly designed and carefully maintained, their bad reputation can become a thing of legend for new camp songs.

Rick Stryker is a professional engineer specializing in helping camps and conference centers identify facility issues and resolve regulatory conflicts. He can be reached at campfc@ptd.net or 570-828-4004.

Originally published in the 2008 July/August issue of Camping Magazine.