9 Essential DIY Dry Toilet Supplies for Off-Grid Living

Setting up an off-grid homestead or converting a school bus presents many layout challenges, but none are more critical than managing human waste. Settling for a complex, water-guzzling flush system or an expensive commercial composting toilet can derail a modest budget and limit mobility. By building a custom DIY dry toilet with the right components, off-grid dwellers can create a highly functional, odor-free system for a fraction of the cost.

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Why Building a DIY Dry Toilet Makes Sense Off-Grid

Commercial composting toilets often cost upwards of $1,000, presenting a massive barrier for budget-conscious builders. A DIY dry toilet offers the exact same biological functionality at a tenth of the price, allowing builders to redirect funds to solar arrays or insulation. This customization is vital for tight spaces like camper vans or 24-foot tiny home trailers where every inch of floor space must be optimized.

The fundamental magic of a dry toilet lies in waste separation. By keeping liquid waste away from solid waste, the system prevents the anaerobic chemical reactions that cause sewage odors. This split system simplifies disposal, turning a high-stakes plumbing challenge into two manageable, non-hazardous tasks.

Urine Diverter – Kildwick Klassic Urine Diverter

The urine diverter is the heart of any successful dry toilet system. It sits directly beneath the seat, capturing liquids in the front bowl while allowing solids to pass through the rear opening. Without this separation, moisture mixes with solid waste, creating the dreaded anaerobic environment that produces foul odors.

The Kildwick Klassic Urine Diverter is a premier choice due to its deep-bowl geometry and high-gloss finish. Molded from durable ABS plastic, its ultra-smooth surface resists stains and sheds liquids instantly. Unlike cheap, flat alternatives, this diverter features a steep drop angle that guarantees all liquid is cleanly funneled into the drain pipe without pooling.

• Material: High-grade, recyclable ABS plastic
• Compatibility: Fits standard 1.25-inch and 1.5-inch waste hoses
• Best Use: Tiny home cabins, converted school buses, and custom wooden toilet boxes

Installation requires cutting a precise opening in the toilet box platform and securing the wide mounting lip. The outlet nozzle must be routed securely to the liquid storage container using a high-quality flexible hose. This diverter is ideal for permanent tiny homes and mobile van builds, but it may require extra bracing in off-road rigs to prevent shifting.

Toilet Seat – Bemis 1500EC Wood Toilet Seat

The toilet seat provides the physical interface for the system, ensuring comfort and structural stability. In a dry toilet, the seat also acts as the first line of defense against odors by helping seal the waste box when closed. A flimsy seat can flex, break, or fail to sit flush against the box top, allowing unpleasant sewer gas to escape.

The Bemis 1500EC Wood Toilet Seat features enameled wood construction that offers a substantial, residential feel. It is equipped with Easy Clean & Change plastic hinges that allow the entire seat to be twisted and lifted off for thorough cleaning in seconds. This lift-off feature is a game-changer for small-space living, where tight clearances make cleaning around toilet hinges notoriously difficult.

• Material: Durable enameled wood
• Hinge Type: Easy Clean & Change plastic hinges
• Sizing Options: Round (16.5 inches) or Elongated (18.5 inches)

Builders must choose between the round and elongated configurations depending on the dimensions of their custom toilet box. The heavy wood construction adds more weight than plastic alternatives, which might be a factor for weight-sensitive van builds. This seat is perfect for those prioritizing a traditional home-like experience, though it is not ideal for ultra-lightweight, minimalist camper conversions.

Urine Bottle – Reliance Products Rhino-Pak 5.5 Gal

A dedicated liquids container collects the diverted urine beneath the toilet box. Without a secure, heavy-duty bottle, the system risks leaks, spills, and catastrophic odor issues inside the living area. The bottle must be tough enough to handle transportation and frequent emptying without structural failure.

The Reliance Products Rhino-Pak 5.5 Gal is engineered from thick, puncture-resistant polyethylene that resists warping and cracking. Its heavy-duty construction means it can support its own weight when full of liquid, which equals roughly 45 pounds. The secure, leak-proof cap and integrated carrying handle make transporting the bottle to a disposal site straightforward and mess-free.

• Capacity: 5.5 gallons (20.8 liters)
• Material: Puncture-resistant, heavy-duty polyethylene
• Dimensions: 14.75″ x 6.25″ x 21.38″

The 5.5-gallon capacity is perfect for couples or solo dwellers, requiring emptying every few days. However, its height requires a toilet box with at least 15 inches of internal clearance. This container is ideal for stationary tiny homes and larger RV conversions, but it is too bulky for low-profile benches in micro-campers.

Waste Bucket – Argee RG5500 5-Gallon Plastic Bucket

The solids bucket collects human waste and the bulking agent, acting as the primary containment zone. It must be sturdy, easy to line with compostable bags, and sized perfectly to fit beneath the solids opening of the urine diverter. A standard, easily replaceable bucket simplifies the management of the dry compost chamber.

The Argee RG5500 5-Gallon Plastic Bucket is molded from heavy-duty HDPE plastic that stands up to constant use without cracking. Its interior walls are completely smooth, preventing any waste or liners from catching during removal. The bucket is sized perfectly to match standard compostable liners and fits snugly under the rear opening of most urine diverters.

• Capacity: 5 gallons
• Material: High-Density Polyethylene (HDPE)
• Height: 14.5 inches

With a height of 14.5 inches, this bucket dictates the minimum comfortable height of the toilet box build. Builders should measure their box carefully to ensure a snug fit that leaves no gap between the bucket rim and the bottom of the diverter. This bucket is an absolute necessity for standard dry toilet setups, but it may be too tall for custom low-profile bench toilets.

Ventilation Fan – Noctua NF-A8 12V Quiet Cooling Fan

A ventilation fan is critical for pulling moisture out of the solids bin and exhausting odors to the exterior of the structure. Continuous airflow dries out the solid waste, speeding up the composting process and preventing mold growth. It also maintains negative air pressure inside the toilet box so odors cannot escape into the living space.

The Noctua NF-A8 12V Quiet Cooling Fan is renowned for its near-silent operation and exceptionally low power draw. Running at a fraction of an amp, it can operate 24/7 on a basic solar setup without draining the battery bank. Its high static pressure capability allows it to push air efficiently through long runs of flexible venting pipe.

• Voltage: 12V DC
• Noise Level: 17.7 dB(A) (exceptionally quiet)
• Dimensions: 80mm x 80mm x 25mm

The fan requires basic 12-volt DC wiring, making it easy to integrate into van or RV electrical grids. It must be mounted inline within a 3-inch PVC or flexible vent pipe routing to the outside. This fan is highly recommended for full-time off-grid homes and vans, whereas weekend campers with short-term buckets may find a fan-less, passive system sufficient.

Bulking Agent – Coco Tek Organic Coconut Coir Brick

Bulking agents are added to the solids bucket after each use to cover waste and absorb excess moisture. This carbon-rich material is essential for starting the aerobic composting process and neutralizing odor instantly. Without a high-quality bulking agent, the solids bucket will remain wet, smelly, and prone to attracting insects.

Coco Tek Organic Coconut Coir Bricks offer an incredibly high expansion ratio, turning a small, easily storable brick into a massive volume of fluffy substrate. Coconut coir absorbs up to ten times its weight in water, drying out solids far more effectively than standard wood shavings. It is completely organic, scent-free, and breaks down rapidly in a compost pile.

• Type: Compressed coconut coir peat
• Yield: Expands up to 2.5 cubic feet per brick
• Application: Soil amendment or dry toilet bulking substrate

The bricks are shipped dehydrated and must be broken down with a small amount of water before use. Off-grid users must manage this moisture level carefully; the coir should be damp like a wrung-out sponge, not soaking wet. It is the perfect choice for long-term off-grid homesteaders, while those with zero access to water for rehydration might prefer dry sawdust.

Compostable Liners – UNNI 100% Compostable Bags

Compostable liners line the solids bucket, allowing for sanitary, touch-free waste disposal. They protect the bucket interior from contamination, reducing the need for harsh chemical scrub-downs. Using these liners makes the transition from toilet box to outdoor compost bin quick and clean.

UNNI 100% Compostable Bags are ASTM D6400 certified, meaning they break down completely in a proper composting environment without leaving toxic residues. Unlike thin grocery bags, these liners are engineered with a durable, puncture-resistant thickness that prevents leaks during removal. They fit 5-gallon buckets perfectly, stretching slightly over the rim for a secure hold.

• Capacity: 5-gallon capacity
• Certification: ASTM D6400 certified 100% compostable
• Thickness: Extra-heavy duty, leak-resistant wall

Because these bags are genuinely compostable, they will begin to degrade when exposed to moisture over extended periods. It is critical to empty the solids bucket at least once a week to prevent the bag from weakening inside the toilet. This product is ideal for eco-conscious off-gridders with active compost piles, but not recommended for those who plan to store waste in a bin for months.

Weatherstripping – Duck Brand Foam Weatherstrip

Weatherstripping seals the microscopic gaps between the toilet box lid and the frame. Even with a powerful exhaust fan, small air leaks can allow odors to escape into a tiny cabin or van interior during windy conditions. A solid seal ensures that air is only drawn in through the toilet seat opening and out through the vent pipe.

The Duck Brand Foam Weatherstrip is made from high-density, closed-cell foam that compresses to form an airtight seal without losing its bounce. The self-adhesive backing sticks firmly to wood, plastic, and painted surfaces, resisting the moisture common in toilet boxes. It is thick enough to close uneven gaps in hand-built wooden structures.

• Material: Closed-cell, high-density foam
• Dimensions: 1/2-inch wide by 1/4-inch thick
• Adhesive: Heavy-duty self-adhesive backing

The mounting surface must be thoroughly cleaned and dried before application to ensure the adhesive cures properly. Over time, friction from opening and closing the lid will wear the foam down, requiring replacement every couple of years. It is an inexpensive, essential upgrade for any DIY builder, though unnecessary for pre-molded commercial units.

Odor Control – Harris Food Grade Diatomaceous Earth

Diatomaceous earth (DE) serves as an organic, mechanical odor-absorber and pest barrier inside the solids bin. In warm weather, dry toilets can attract fungus gnats or fruit flies if the composting pile remains damp. DE naturally dehydrates these pests and absorbs lingering odors without the use of harsh synthetic chemicals.

Harris Food Grade Diatomaceous Earth is a pure, chemical-free powder that is completely safe to handle in tight living quarters. It acts as a mechanical insecticide, slicing through the exoskeletons of insects on a microscopic level while remaining completely harmless to humans and pets. A light dusting over the solids pile keeps pests at bay while speeding up the drying process.

• Grade: Food grade (non-toxic)
• Volume: 4 lb bag with included powder duster
• Active Ingredient: 100% natural freshwater Diatomaceous Earth

The powder is incredibly fine and can create a dust cloud if dumped carelessly into the bucket. Using the included handheld squeeze duster allows for precise, mess-free application directly onto the waste pile. This is an indispensable tool for off-gridders living in humid or warm climates, but it may be unnecessary during cold winter months.

How to Manage Ventilation and Moisture in Small Spaces

Managing moisture is the single most critical factor in keeping a dry toilet odor-free in compact environments like camper vans or 24-foot tiny homes. Solid waste is naturally moist, and when trapped in a sealed box without airflow, it quickly turns anaerobic. To prevent this, active ventilation must pull damp air out of the holding chamber continuously, forcing fresh air to draw through the seat opening.

When routing vent pipes, off-grid builders should run the ducting through the floor or side wall rather than the roof to minimize the risk of rainwater leaks. Utilizing a 3-inch flexible hose connected to a low-draw 12V fan ensures a steady stream of air is exhausted outside. It is wise to install a slight downward slope in the exterior portion of the pipe to prevent condensation from trickling back down into the fan motor.

In humid climates, passive venting is rarely sufficient to keep the waste pile dry. Active fans must run continuously, drawing power from the cabin’s solar battery bank. If condensation becomes an issue inside the toilet box, adding a small piece of insulation around the vent pipe can stabilize internal temperatures and keep the air moving smoothly.

Essential Maintenance Rules for Odor-Free Dry Toilets

The absolute golden rule of dry toilet maintenance is the strict separation of liquids and solids. When urine mixes with feces, it creates a chemical slurry that is nearly impossible to keep odor-free without heavy chemicals. Users must sit down to use the toilet to ensure the anatomy aligns perfectly with the urine diverter’s collection zones.

Emptying schedules must be kept consistent to avoid overloading the system. A 5-gallon solids bucket typically lasts two adults about one to two weeks before requiring disposal, while a 5-gallon urine bottle needs emptying every two to three days. Neglecting the liquids bottle can lead to overflows, which are both unpleasant to clean and source points for persistent odors.

For cleaning, avoid using harsh chemical disinfectants like bleach, which kill off the beneficial microbes needed to break down the solid waste. A simple spray bottle filled with a mixture of water, white vinegar, and a few drops of tea tree oil is highly effective. Spritz the diverter and seat regularly to keep the system fresh without disrupting the natural decomposition process in the bucket below.

Building a DIY dry toilet is a practical, liberating step toward self-reliance that keeps money in the bank and water in the tank. Armed with these nine essential supplies and a solid understanding of waste separation, any off-grid dweller can build a system that rivals expensive commercial units.