7 Best Urine Separator Upgrades For Diy Composting Toilets
Optimize your setup with our 7 best urine separator upgrades for DIY composting toilets. Explore these practical improvements and upgrade your system today.
Mastering the art of a DIY composting toilet starts with one non-negotiable reality: separation is the key to an odor-free experience. If liquids mix with solids, the anaerobic bacteria take over, turning a simple bathroom solution into a pungent nightmare. Choosing the right urine separator ensures the system functions efficiently, keeping the composting process aerobic and manageable for long-term off-grid living.
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Johnny Compost Original: The DIY Standard
The Johnny Compost Original remains the gold standard for those building their own toilet from scratch. It features a straightforward, high-walled design that successfully directs fluid into the collection point while shielding the solid waste area. This separator is purpose-built for simplicity and reliability in a variety of enclosure styles.
Because it lacks unnecessary bells and whistles, it fits perfectly into modest DIY builds where space and budget are primary constraints. The plastic is thick enough to withstand standard wear and tear without warping under pressure. This is the go-to choice for the minimalist builder who wants a proven, no-nonsense component that just works.
Separett Privy 501: Best All-in-One Kit
When seeking a complete solution, the Separett Privy 501 stands out by including both the diverter bowl and a matching seat. This integration eliminates the frustration of trying to align a separate bowl with a toilet seat, which is a common point of failure in amateur builds. The kit is designed with a rear splash guard that provides extra insurance against accidental overflow.
This option is perfect for those who want to reach a functional build phase quickly without fabricating additional parts. It is exceptionally popular in Scandinavian-style cabin builds where hygiene and ease of maintenance are paramount. The Privy 501 is the right move if you prioritize a professional-grade finish and a streamlined installation process.
Kildwick Klassic: Most Ergonomic Design
Ergonomics often take a backseat in DIY toilet builds, but the Kildwick Klassic challenges that oversight with a carefully contoured shape. The design focuses on the physical comfort of the user, ensuring that the separation process is intuitive and clean. Its shallower profile makes it an excellent choice for smaller boxes or compact van cabinetry.
The material quality feels superior to entry-level plastic diverters, offering a solid, high-quality feel under pressure. For those who prioritize comfort for long-term daily use, this investment pays dividends in user experience. Choose the Kildwick Klassic if the toilet is going into a high-use dwelling where comfort is just as important as function.
We-Pee Funnel: Best Low-Profile Option
Space is the ultimate luxury in tiny homes and van conversions, and the We-Pee Funnel addresses this by being the lowest-profile option on the market. It functions essentially as a high-efficiency catch basin that can be tucked into almost any custom seat opening. Its small size allows for more creative, compact framing underneath the toilet bench.
This diverter is specifically for the creative builder who is designing a custom, space-saving throne from reclaimed materials or tight cabinetry. While it requires a bit more planning for mounting and plumbing, the space savings are unrivaled. If every cubic inch of your dwelling counts, this is the most logical starting point for your build.
StrumpfTastic Separator: Best for Custom Builds
The StrumpfTastic separator is engineered with modularity in mind, making it the favorite for custom builds that deviate from standard rectangular boxes. Its unique geometry allows for flexible installation, accommodating various hose positions and drainage angles. This level of adaptability is rare in the pre-fab separator market.
This product caters to builders who are working with irregular dimensions or unique plumbing runs where standard diverters would fail to fit. The construction is robust, and the thoughtful design of the spout makes sealing the drain hose far easier than with competing models. It is the definitive choice for the complex, unconventional, or highly customized off-grid toilet installation.
Compoost Toilets Diverter: Easiest to Clean
Hygiene is the most common concern for those new to composting toilets, and the Compoost Toilets diverter addresses this by minimizing seams and crevices. Its smooth, non-porous finish prevents buildup and makes regular sanitation a quick wipe-down affair. The wide-mouth design ensures that everything flows exactly where it needs to go without sticking.
This diverter is ideal for users who are particularly concerned about odors or potential bacterial growth within the separator housing itself. Because the design is so streamlined, there are fewer places for residue to hide, which significantly reduces the frequency of deep cleaning. If low maintenance is the primary goal, this is a top-tier contender for the build.
Trelino Urine Diverter: Best for Durability
The Trelino diverter is built from high-grade, food-safe plastic that stands up to the corrosive nature of urine over many years. Its structure is rigid, preventing the cracking or bowing that often plagues cheaper injection-molded alternatives. This is a “buy it once” component that fits seamlessly into a high-end, long-term living setup.
Trelino components are designed to be part of an integrated, aesthetically pleasing system, making them the best option for owners who want their toilet to look like a permanent piece of furniture. While it carries a premium price, the lifespan and build quality justify the cost for those committed to full-time alternative living. It is the best choice for those who demand reliability and a clean, modern aesthetic.
How to Choose the Right Diverter Material
Selecting the right material is a balance between weight, cost, and long-term durability. Most high-quality diverters are made from ABS or polypropylene plastic, both of which are resistant to chemical reactions and easy to clean. Avoid cheaper, thinner plastics that may become brittle over time when exposed to cold or cleaning chemicals.
Consider the surface finish carefully, as a glossy, non-porous finish will always outperform a textured surface in a sanitary context. Matte finishes may look sophisticated, but they often trap microscopic residues that can contribute to odor development. Always prioritize smooth, continuous surfaces that facilitate efficient runoff toward your collection container.
Installing Your Diverter for a Leak-Proof Seal
A successful installation hinges on the connection between the diverter spout and your drainage hose. Use high-quality silicone or food-grade tubing to connect the diverter to your urine reservoir, ensuring there is a constant downward slope to prevent pooling. Even a slight uphill kink in the tubing will create a “p-trap” that holds urine, eventually leading to odors.
Secure the diverter to the toilet bench using stainless steel hardware to prevent rust in the humid environment of a bathroom. Use a bead of waterproof, mildew-resistant sealant around the base of the diverter where it meets the wood framing to prevent any stray drips from entering the solid waste compartment. A dry, sealed separation unit is the single most important factor in a scent-free bathroom.
Managing Urine Bottles and Odor Control Tips
Proper urine management requires a high-quality, opaque container that can be sealed air-tight for transport. Opaque containers are essential because sunlight exposure encourages algae growth and increases the pungent odor of the waste as it breaks down. Incorporate a simple overflow indicator or a translucent level-check window if your system allows for it.
To keep odors at bay, consider adding a small, low-voltage PC fan to the solid waste container to maintain a constant vacuum through a vent hose. This pulls air down and out of the toilet, effectively stripping the room of any smells before they can escape. Always remember that the diverter is only one part of the system; air management is the second half of the equation for total comfort.
A well-designed urine separation system is the foundation of a dignified and odor-free off-grid lifestyle. By selecting the right hardware and executing a precise, leak-proof installation, you can build a system that rivals the convenience of traditional plumbing. Approach your build with care, focus on the details of the drainage path, and enjoy the freedom that comes with true independence.
Frequently Asked Questions (FAQs)
What is a urine separator in a DIY composting toilet?
A urine separator is a molded insert that diverts liquid waste away from solid waste inside a DIY composting toilet. Keeping liquids separate prevents anaerobic bacteria from multiplying, which eliminates the rotten sewage smell typical of mixed waste buckets. Most separators channel urine through a front funnel into a jug or drain line, while solid waste falls through the rear opening into a lined bucket. Installing an upgraded unit with wider margins provides a cleaner collection boundary and prevents spills.
What does an anti-splash screen upgrade do in a urine diverter?
An anti-splash screen upgrade prevents urine droplets from bouncing out of the diverter funnel and keeps solid debris from clogging the drain line. These screens usually consist of stainless steel mesh, perforated silicone domes, or porous drain stones sitting directly over the drain opening. They break the surface tension of high-velocity urine streams, reducing mess and odors. Clean the screen weekly by lifting it out with pliers and rinsing it under hot water to clear mineral scale.
How do I seal a urine separator into a DIY plywood composting toilet?
Secure the urine separator by screwing its mounting flange to the underside of the plywood box lid using stainless steel pan-head screws and waterproof silicone sealant. Cut the top opening with a jigsaw so the diverter rim fits flush beneath the toilet seat hole. Apply a continuous bead of 100% silicone caulk between the plastic rim and the finished plywood to stop moisture from seeping into the wood grain. Clamp the unit gently for 24 hours until the adhesive cures before mounting the hinges.
How do I plumb a urine separator drain line to an external tank in an off-grid cabin?
Plumb a urine separator to an external container by attaching a rigid, smooth-bore PVC pipe with a continuous downward slope of at least one-quarter inch per foot. Connect the diverter’s threaded drain outlet to a flexible silicone coupler, transitioning to three-quarter-inch or one-inch schedule 40 PVC through the floor. Avoid corrugated ribbed hose because crystalline struvite deposits collect in the ridges and cause severe clogs. Run the pipe straight into a vented exterior tank or French drain pit below the frost line.
Which is better for a camper van, a plastic or stainless steel urine separator?
Plastic urine separators are generally better for camper vans because ABS and acrylic models are lightweight, budget-friendly, and resistant to corrosive ammonia damage. Stainless steel separators offer superior scratch resistance and aesthetic appeal, but lower-grade metals can pit and tarnish when exposed to acidic urine over time. High-impact ABS plastic weighs under two pounds and flexes slightly with vehicle road vibration without cracking. For camper conversions where weight and road stress matter, smooth-finish molded plastic like Kildwick or Privy inserts performs more reliably.
How much does it cost to upgrade a basic DIY composting toilet urine diverter?
Upgrading a basic urine diverter costs between $40 and $180, depending on whether you purchase a pre-molded insert or build a complete custom kit. Entry-level molded plastic funnels run from $45 to $70, while premium fiberglass or stainless inserts cost $100 to $160. Additional hardware upgrades—such as anti-odor rubber flapper valves, brass drain fittings, and flexible hose couplers—add another $15 to $35 to your total material budget. You can complete the replacement in roughly two hours using basic hand tools.
Why is urine splashing back out of my DIY composting toilet separator?
Urine splashes back out of a separator when the drain hole is too small, air cannot vent from the plumbing, or the drop angle is too shallow. Air locks occur if your drain hose sags or your collection jug lacks an air vent hole, forcing liquid to back up rapidly. Inspect your drain pipe to ensure it maintains a steep, uninterrupted decline toward the tank. If splashing occurs during urination, add a stainless steel mesh strainer into the diverter basin to break droplet velocity immediately.
Is upgrading to a 12-volt exhaust fan necessary for an indoor DIY composting toilet?
Installing a 12-volt exhaust fan is highly recommended for indoor DIY composting toilets because active airflow maintains negative pressure and vents residual moisture outside continuously. Passive vents often fail on warm or humid days when air pressure balances between the indoor living area and the outdoors. A tiny computer-style blower drawing between 0.05 and 0.2 amps pulls air downward through the urine diverter and solids bin, discharging odors through a roof cap. This upgrade stops odors from entering living spaces even when opening the lid.
