Thetford Porta Potti 335 Portable Toilet review
By Tom Calder
A well-proven, no-nonsense portable toilet that needs no power and empties cleanly via its rotating spout. The 335 is the compact model in the range, so it suits one or two people rather than a full household over several days.
- Best for
- Caravan, campervan and boat owners, or households wanting a compact self-contained loo for power cuts or a burst-main.
- Skip it if
- A whole household may need it for days at a time
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.We earn a commission if you buy through the retailer links on this page. It doesn't change our verdict. How we make money →
Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Reliable, long-established Thetford design with a hygienic rotating pour-out spout and secure lid latch
- Fully self-contained and light (3.3kg net, per Thetford) with a 10L flush and 10L waste tank, no plumbing or power needed
- Simple manual piston flush that just works, with widely available spare parts and toilet fluids
Worth knowing
- Modest waste capacity of roughly 27 flushes means frequent emptying if several people rely on it
- Needs toilet chemicals and a suitable disposal point (a proper waste dump or WC), which takes some planning in an emergency
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Our review
The Thetford Porta Potti 335 is the compact model in a range that has served caravans and boats for decades: a 10 litre flush tank on top of a 10 litre waste tank, a piston pump flush and a swivel spout for emptying, at 3.3 kg. For a household with no water for a few days it is a proper seat and a sealed tank, and its only real limit is how often you empty it.
What it is
Thetford's specification gives a 10 litre waste tank and a 10 litre flush tank, overall dimensions of 313 mm high by 342 mm wide by 382 mm deep, a seat height of 308 mm and a net weight of 3.3 kg. There is a level indicator on the waste tank, a spout stop for pouring out and a hold-down kit for fixing it in a vehicle. The manual rates it for a load of up to 120 kg and recommends three or four short pumps of the piston per flush rather than one long one.
Thetford's general guidance is that the waste indicator gives roughly 27 to 33 flushes depending on the model and the fresh tank about 56 flushes on average. For the 335, with its small tanks, plan on the lower end: for two people that is a couple of days between empties, for a family of four about one.
Using it when the water is off
A burst main or a boil water notice does not stop the loo working if you can fill the cistern by hand, so a chemical toilet is for the rarer case where there is no water to spare or the drains are backing up. Our guide to what to do when the water supply fails sets out the order of priorities. Fill the flush tank from stored water, add the dose of tank fluid to the waste tank, and use the toilet paper Thetford specifies, since ordinary paper is slow to break down.
Emptying is the part people forget. Thetford's manual says the waste tank is to be emptied only at an authorised waste disposal point: a chemical disposal point at a campsite, marina or some household recycling centres. At home the practical option is your own WC, with the lid of the spout open to let air in, and never a surface drain or a septic tank with the common blue fluids, which kill the bacteria the tank relies on.
How it compares
On the emergency toilets page the Porta Potti 565P is the larger sibling, with a 21 litre waste tank and 15 litre flush tank: twice the capacity and a taller, more comfortable seat for more money and weight. The Trobolo Wandago and the Kildwick Piccoloo separate urine from solids and need no water or chemicals, which makes them better for a long outage but less familiar to use. Cleanwaste's gelling bags and a bucket toilet are cheaper still and need no emptying, only a bin. The 335 is the right size for one or two people, or a boat or campervan where it earns its keep all year.
Our verdict
Buy it if you want a real seat and a sealed tank for a couple of people and can empty it every day or two. Skip it for a family that may be without water for a week; the 565P or a separating toilet gives you more days between empties, and bag toilets avoid the chore entirely. Buy the fluid and the right paper at the same time, and run a flush or two before you need it.
A researched review, built from the maker's specs, manual and UK listings; facts checked 2 Nov 2026. Sources: Thetford: Porta Potti 335 portable toilet specifications; Thetford: Porta Potti user manual (PDF); Thetford FAQ: how the Porta Potti level indicator works.
Who shouldn't buy this
Don't buy the 335 if a whole household may need it for days at a time; the taller 365 or a larger cassette model gives more capacity between empties.
Key specs
| Type | Portable chemical toilet (manual piston flush) |
| Capacity | 27 |
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
If this isn’t the one
Best for A full-height portable toilet to see a household through a water or power outage.
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for A portable separating toilet for a household backup, campervan or garden room, with no water or chemicals.
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for A ready-assembled wooden separating toilet for a garden room, cabin, boat or campervan, used by one or two people.
as of 2 Nov 2026, 16:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Questions
How many flushes does the Porta Potti 335 give?
Thetford's general figure is about 27 to 33 flushes before the waste indicator shows full and about 56 flushes from the fresh tank, depending on the model. The 335 has 10 litre tanks, so expect the lower figures.
Where do I empty a chemical toilet?
Thetford says only at an authorised waste disposal point, such as a chemical disposal point at a campsite. At home, a WC is the practical option. Never empty it into a surface drain, and not into a septic tank if you use a formaldehyde-based fluid.
How heavy is it?
Thetford gives 3.3 kg net when empty. A full 10 litre waste tank adds about 10 kg, which is still easy to carry by the handle.
Can I use ordinary toilet paper?
Thetford's manual says not to. Use a quick-dissolving paper made for chemical toilets so the tank empties cleanly.
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