Thetford Porta Potti 565P review

What it is

A two-part cassette toilet. The top half holds 15 litres of flush water and a piston pump; the bottom half is a sealed 21-litre waste-holding tank with a level indicator, which unclips and carries away to be emptied. Thetford gives the size as 448 mm high, 388 mm wide and 450 mm deep, with a seat height of 443 mm, and the weight as 4.9 kg empty. The bowl is larger than on Thetford's smaller models, and there is a toilet-roll holder built in.

The 565 series manual gives a maximum load of 120 kg and recommends three or four short pumps to flush. The pump needs no batteries, which is the difference from the electric-flush 565E.

In an outage

When the mains water goes off, an ordinary toilet can still be flushed with a bucket of stored water, but that uses water you may need for drinking. A cassette toilet uses a small amount of its own flush water and keeps waste sealed and treated, which matters for hygiene in a home with children or older people. Our guide to what to do with no water supply covers the bigger picture.

It needs toilet chemicals to work properly: an additive in the waste tank to break down waste and control smells, and a rinse in the flush water. Thetford's dosing for its Aqua Kem Blue is 60 ml per 20 litres of waste-tank capacity with 2 to 3 litres of water, lasting up to five days. Its manual warns that using the wrong products could damage the toilet, and that ordinary toilet paper may cause clogging.

Emptying and the limits

This is the part to plan for. Thetford's manual says emptying is only allowed at an authorised waste dump, and to take the tank to an authorised disposal point; it says to empty when the level indicator turns red. Campsites and caravan sites have chemical disposal points connected to the sewer. Never empty a chemical toilet into a drain, a watercourse or the ground.

Thetford also says never to clean it with household cleaners, which can damage the seals, and not to use it in cold weather unless it is somewhere heated; drain it completely if there is any risk of frost.

How it compares

On our emergency toilet comparison, the smaller Thetford 335 uses the same principle in a lighter, lower package. A bucket toilet with gelling bags, or Cleanwaste's bag kits, avoid chemicals and cassette emptying, because waste is sealed in bags and disposed of as their makers direct, at the cost of comfort and a supply of bags. Separating toilets such as the Trobolo WandaGO or Kildwick PiccoLoo divert urine and need no chemicals.

Our verdict

If you want something that feels close to a normal toilet through several days without water, and you have somewhere to empty it, the 565P is the most comfortable option on our list. If you have no access to a disposal point, a bag-based toilet is the more practical choice.

How big are the tanks on the Thetford 565P?

Thetford gives 15 litres for the flush-water tank and 21 litres for the waste-holding tank, each with a level indicator.

Where can I empty a Porta Potti?

Thetford's manual says emptying is only allowed at an authorised waste dump or disposal point, such as the chemical disposal points on campsites. Never empty it into a drain, a watercourse or the ground.

Do I need special chemicals for the 565P?

Yes. Thetford recommends its additives for the waste tank and flush water, and warns that the wrong products could damage the toilet. Don't use household cleaners, which can damage the seals.

Does the 565P need batteries?

No. The 565P flushes with a hand-operated piston pump. The 565E is the battery-powered electric-flush version.