Choosing a portable toilet comes down to matching waste tank capacity, seat height, and chemical compatibility to your specific use case — whether that’s camping, van life, or event hosting.
For the full breakdown, see our best Portable Toilet guide.
The right portable toilet saves you from miserable middle-of-the-night emptying runs and odor problems that spoil a trip. Most buyers get tripped up on one of three things: picking a model too small for their group, ignoring seat height (which matters more than you’d think), or dumping the wrong chemicals. Here’s what actually matters — in the order it matters.
Waste Tank Capacity: The First Decision
Waste tank size dictates how often you’ll be emptying the thing. For a weekend trip with two people, a 10-liter tank works fine — you’ll empty it once. A family of four on a week-long trip needs at least 20 liters, or you’re dealing with daily dumping. Some models, like the Thetford Porta Potti 165, pair a 21-liter waste tank with a 15-liter flush tank, which means fewer refills on both sides. The manual for most units recommends adding 2 to 3 liters of water to the waste tank before closing the valve — this gives the chemicals room to work.
Seat Height, Ergonomics, and Fit
Lower tanks mean lower seats, and a low squat position is hard on knees and hips, especially getting up in the dark. Models with smaller waste tanks (15 liters or under) sit lower. If anyone in your group has mobility concerns, prioritize a unit with a bench-height seat — it’s worth the extra size. Also check the packed dimensions: a compact unit is easier to carry but may feel cramped inside. For wheelchair access at an event, you need a wider door and interior, which means a completely different class of unit.
Chemicals, Paper, and What Not to Flush
| Chemical Type | Where It Goes | Best For |
|---|---|---|
| Pink liquid | Flush tank | Cleaning and preventing deposits |
| Blue liquid | Waste tank | Breaking down solids, controlling odor |
| Green liquid | Waste tank | Septic-safe; required at some campsites |
| Pod drops | Waste tank | Dissolvable, mess-free, works immediately |
| Nappy sand (DIY) | Waste tank | Cheap, eco-friendly, septic-safe in small amounts |
Dosage matters: too little and odors win; too much harms the environment. Stick to the amount on the bottle. For toilet paper, use fast-dissolving brands only (Thetford’s Aqua Soft works). Regular paper clumps, wet wipes form solid blocks, and diapers or sanitary items will destroy the tank mechanism — never flush them.
Top Models for Different Needs
For small van spaces, the Thetford Porta Potti 135 is compact and sturdy. For rough camping where durability beats comfort, the Reliance Luggable Loo is a simple bucket-style unit that takes a beating.
Cleaning and Storage
Empty the entire system after every trip and rinse thoroughly. Spray silicone on the rubber seals to prevent them drying and cracking — a cracked seal is a guaranteed odor leak. If your unit lacks an Aqua Rinse feature, expect more manual scrubbing of the bowl. Check campsite rules on chemical types before you go; some disposal points reject blue liquids entirely.
FAQs
How often do I need to empty a portable toilet?
With a 10-liter waste tank, expect to empty it every 2–3 days for two people. A 20-liter tank doubles that interval. Weekend-only users with small tanks typically empty once per trip.
Can I use regular toilet paper in a camping toilet?
Regular toilet paper clumps and clogs the mechanism over time. Fast-dissolving paper designed for portable toilets prevents blockages. Use as little paper as possible if you’re in a bucket-style unit.
What’s the difference between blue and green toilet chemicals?
Blue chemicals break down waste and control odor but are not septic-safe and are banned at some campsites. Green chemicals are natural and septic-safe but may require larger doses. Check your campsite’s rules before buying.
References & Sources
- The Camping and Caravanning Club. “Camping Toilets: A Complete Guide.” Covers tank capacities, chemical types, and maintenance steps.