An incinerator toilet costs $800. A shower combo toilet costs $600. Both claim to save space in small RVs. But neither tells you the hidden costs that determine whether they’re actually worth it. I spent 6 months with an incinerator toilet in a Class C and found myself standing in the rain outside my shower because the combo unit was too small to use comfortably.
Space-constrained RVs face a fundamental trade-off: do you prioritize the toilet or the shower? Incinerator toilets eliminate water usage entirely — no fresh water, no black tank, no holding tank. Shower combos combine your shower and toilet in one compact unit, freeing floor space but sacrificing privacy and comfort. Both solutions solve the same problem (limited space) in radically different ways.
The Space Problem in Small RVs
Standard RV bathrooms require space for:
– Toilet bowl and clearance (minimum 30×30 inches)
– Shower stall (minimum 30×36 inches)
– Vanity/sink area (optional but desirable)
– Door swing clearance
In a Class B van or small Class C, this adds up to 40-60 square feet dedicated to bathroom functions. For an 80-square-foot living space, that’s half your floor area going to one room.
Incinerator toilets solve this by eliminating the toilet’s footprint entirely. The unit is roughly 14×14 inches — smaller than a standard toilet — and requires no water lines, no black tank, and no vent pipe. You can install it in a corner that wouldn’t accommodate a conventional toilet.
Shower combos solve this by combining the shower and toilet into one enclosed space. The unit is roughly 30×36 inches — the same footprint as a standard shower stall — but eliminates the need for a separate toilet area.
Incinerator Toilets: How They Work
Incinerator toilets burn waste at temperatures of 1200-1600°F using electric heating elements. The process takes 45-90 minutes and converts everything to sterile ash. No water, no chemicals, no black tank.
Power requirements: Most incinerators run on 120V AC (shore power or generator) or 12V DC (battery). Some models have dual-voltage capability. Power consumption during a burn cycle: 400-800 watts for 45-90 minutes.
Capacity: Most units handle 5-10 flushes before the ash pan needs emptying. This varies by user weight, diet, and usage frequency. A couple boondocking for a week will rarely need to empty the ash pan. A family of four will need to empty it every 2-3 days.
Noise: The incineration process produces a low humming sound (similar to a space heater). It’s not silent but it’s not disruptive — quieter than a refrigerator compressor.
Shower Combos: How They Work
Shower combo units integrate a toilet, shower stall, and sometimes a small sink into one molded fiberglass enclosure. The toilet is usually a standard gravity flush or manual pump model. The shower curtain or door encloses the entire space.
Space savings: Eliminates the need for a separate shower stall. The combined unit occupies roughly the same footprint as a standard shower stall (30×36 inches) but replaces both the shower and toilet areas.
Privacy trade-off: You shower in the same space where you use the toilet. While this doesn’t bother most adults, it can be uncomfortable for families with children or guests.
Ventilation: Most combo units require a roof vent fan (standard RV vent fan works) to manage humidity. Without proper ventilation, condensation builds up and promotes mold growth.
Head-to-Head Comparison
|| Feature | Incinerator Toilet | Shower Combo |
||———|——————-|————–|
|| Upfront cost | $700-$1,200 | $400-$800 |
|| Installation complexity | Moderate (electrical + mounting) | Moderate (plumbing + mounting) |
|| Water usage | Zero | Standard (2-3 gal per flush) |
|| Black tank capacity impact | None (no waste goes to tank) | Normal |
|| Power consumption | 400-800W per burn cycle | None (gravity flush) |
|| Maintenance | Ash pan emptying, heating element replacement every 2-3 years | Standard toilet maintenance |
|| Odor | Minimal (sterilized ash, sealed system) | Standard RV toilet odor |
|| Noise | Low hum during burn cycle | Silent |
|| Space saved | Eliminates toilet area (~14×14 inches) | Combines shower + toilet into one area |
|| Best for | Boondockers, off-grid, eco-conscious | Families, full-timers, budget-conscious |
The Hidden Costs Nobody Mentions
Incinerator hidden costs:
– Replacement heating element: $60-$120 every 2-3 years
– Replacement fan motor: $30-$50 every 5-7 years
– Higher electricity consumption when boondocking (drains batteries faster)
– Cannot incinerate non-organic materials (toilet paper, feminine products, plastics) — you still need to dispose of these separately
Shower combo hidden costs:
– Reduced shower comfort (standing over a toilet while showering)
– Higher water consumption (standard flush + shower water in same enclosure)
– More frequent black tank emptying (waste goes to tank normally)
– Potential mold/mildew issues if ventilation is inadequate
Real-World Experience
Incinerator in a Class C (6 months): The incinerator eliminated black tank worries entirely. I boondocked for 14 days without needing to dump. The ash pan was emptied once. The unit’s noise was noticeable but not annoying — I stopped hearing it after day two. The $800 investment paid off in convenience and eliminated all black tank chemicals. Downsides: couldn’t flush toilet paper (had to bag it and carry it out), and the 45-90 minute burn cycle meant planning ahead.
Shower combo in a Class B van (3 months): The space savings were real — I gained enough room for a small table that I used for meals. But showering with the toilet bowl right in front of you is psychologically uncomfortable. My partner hated it. The black tank filled quickly because we were using standard flush volumes in a small vehicle. We ended up installing a separate composting toilet after 3 months.
Here’s My Take
If you’re boondocking more than 2 weeks per trip, the incinerator toilet at $800 is worth every penny. Eliminating black tank management changes your entire camping experience — you’re not counting gallons or rushing to dump stations. If you’re staying at campgrounds regularly, the shower combo saves money upfront but costs more in water bills and compromises comfort. The real winner for most RVers is a middle ground: keep your standard toilet but upgrade to a low-flush model and add a composting toilet as a secondary option for dry camping.
References
– Separett Villa Incinerator Toilet Specs: https://www.separett.us
– Thetford Shower Combo Units: https://www.thetford.com
– Incinerator Toilet Comparison Guide: https://www.rvtravel.com
– Small RV Bathroom Design Ideas: https://www.popularmechanics.com