If you have a motorhome, caravan or campervan then you probably have a toilet on board where the waste goes into a cassette. The cassette normally contains a toilet fluid (often blue or green in colour) which is designed to break down the solids, and eliminate any bad smells. Some people use Bio washing liquid as its cheaper and it does work but not as well as the proper toilet fluid.

There are some issues with using chemicals and there are now some eco friendly chemicals available.

A quick tip… To save money we bought cheap toilet fluid from our local camping shop. It was rubbish. It looked good but we found we had to use double the amount to get it to work, so it was not money saving at all! We bought some Elsan concentrated fluid at a motorhome show for £10 and its been excellent with a 4L bottle lasting well over a year with regular use.

The SOG toilet

The alternative to keep buying chemicals is to install a SOG tiolet. This works buy installing a small fan connected to the toilet which switches on when the cassette blade is opened thus drawing any smells away from the cassette and out through a charcoal filter to the outside. This eliminates the need for chemicals as you only need to put water in the cassette.  N.B. some countries have banned chemical toilet waste being put down the disposal points.

We had thought about installing one for some time and when ebay had a 20% discount day it seemed too good an offer not to buy one. We have a Thetford C200 cassette which is very common. SOG have developed several different kits for different cassettes and fixings so if purchasing ensure you buy the correct kit.

Although we bough out kit from ebay, Amazon sell the full range of SOG kits, accessories and spares. Click HERE to view on Amazon.

The kit comes with good instructions but I also found some additional instructions HERE on a PDF.

The SOG toilet installation

The kit arrived and contains the door fan kit, extractor tubing, switch and fittings.

2016-05-08 14.41.32

1 – Measure where the hole needs to be drilled in the toilet door. With a hole cutter drill the hole and the mark out where the outer cover will fit and then drill the small holes for the outer screws.

2016-05-08 19.24.53

2 – Fit the outer casing to the outside of the door. I used some Sikaflex 512 adhesive sealant around the outer section and screwed it to the door.

2016-05-08 19.34.25

3 – Fit the fan through the newly made hole and mark the screw holes on the inside and drill the pilot holes for the screws and fit the fan. I left it a few days for the sealant to dry before continuing with the rest of the work.

2016-05-08 19.38.39

4 – The saddle bracket needs removing. The provided instructions are not very clear so you need to first remove the bracket which has the linkage to the blade opener knob (which is the grey sliding knob inside the van). Once this is removed it will dangle down and you can remove the three screws that hold the saddle bracket. This will just drop down after screws are removed.

2016-05-14 09.26.18

2016-05-14 09.27.54

2016-05-14 09.29.42

This bracket needs to be carefully modified because it contains a raised ridge that opens the pressure valve when the cassette is inserted and with the SOG the pressure valve is removed from the cassette. I have marked the bracket in red so you can see what needs to be removed.

Once the bracket has been cut refit the saddle bracket and the linkage.

2016-05-14 09.32.48

2016-05-14 09.40.44

5 – Mounting the L shape bracket containing the switch. This takes some careful positioning. You have to position it so when the blade is closed the switch is pressed in. Ensure the top of the bracket is slightly above the base line of the white plastic mechanism so it does not foul the cassette when it is pushed in. Clean the plastic wall with some meths or alcohol, remove the adhesive backing and carefully stick the switch bracket in place. The kit also contains plastic rivet which goes through the small hole in the bracket. This is not easy to drill due to the confined space so I found a 5mm drill bit and manually made the hole by hand. It was quite easy. Push the rivet through and then hammer the centre locking pin.

2016-05-14 11.26.38

2016-05-14 11.26.49

6 – Electrics. You need to find a + and – 12v DC feed which should be close to the toilet. A multi meter is a good tool to check the polarity. In many motorhomes the brown cable is normally + and blue – but double check. After checking switch off the 12v in the motorhomes and connect the 12v to the wiring harness. The kits comes with a couple of line connectors but in my case there was a choc block already being used so I just unscrewed the existing connections and joined the harness to this.

2016-05-14 11.27.01

7. Join the other end of the harness to the fan on the door. The kit comes with some spade connectors so carefully cut the harness to the right length (ensuring you have enough cable so the door will open and close easily) and crimp the spade connectors on to the bare cable ends. Lastly use the provided cable clips and cables ties to tidy the cables.

2016-05-14 11.24.48

8. Remove the pressure valve on the cassette. Turn the valve fully anticlockwise until it stops and then turn back about 1mm and the valve should just lift out. Replace the valve with the green ventilator connector.

2016-05-14 10.43.07


That’s it. It all works.

2016-05-14 11.24.55

2016-05-14 11.26.16