Wanderer Motorhome Page 15

Driving in France?
Then this web site is a must:

email Brian,

Environmentally Safe Toilet Treatment for motorhomes, caravans and boats:

For a Holiday with a difference in a Motorhome, see this link:

Great Ormond Street Hospital
Children's Charity 
Great Ormond Street Hospital, Children's Charity, 40 Bernard Street, London.  WC1N 1LE
Tel: 020 7239 3000 
Click on the link to donate

As author and maintainer of this web site. I do not save, retain, or sell  any email addresses of those who email me. Should you not get a reply from me, please send again, I might have missed it in my spam catcher!

Additions to Motorhome pages:-
1.Fitting New Automatic Water System Pump
2.Winterising the water pump.
3.Water Tank Level Meter-modification to electronic circuit

4.Basin Mixer Taps - tip & how to repair a dripping tap.
5.Extending Fresh Water Drain Tap to Outside

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Our MH has now been sold so this web site will not be updated again

[click above for pictures]

Due to my age, 80 years old, and health reasons we are forced to give up the pleasures of a motorhome,  and has now been sold.

Description of the motorhome can be seen through out the pages of my web site here.

The MH has MOT until MAR 2017 and its mileage is 109224

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Contents:    1. Algae in the Thetford Toilet Fresh Tank.
                  2. Algae Build up Solution
                  3. Thetford Toilet Cassette Level indicator
                  4. Vehicle Odours.
                  5. Thetford Toilet Fault
                  6. Toilet Seal Fault, replacing the seal.

Letter received from Thetford:
Good Morning Mr Walters, 
Please find information which we hope will help to resolve the problem you have been experiencing. 
Kind Regards, 
Karen Bliss 
Customer Services.

Algae in the Thetford Toilet Fresh Tank.
Removal of Water Tank Algae Build Up.

If water is left in a sealed tank or container, soon bacteria and/or algae will develop.  Light and temperature will speed up the growth.  To protect themselves from being flushed away, these micro-organisms will form a slimy film (often grey or brown) on the walls.  The active ingredients in our fresh water tank additive Aqua Rinse will prevent adherence to the walls.

Prior to using your unit again, may we therefore recommend the following course of action.

Fill the waste tank with a solution of fresh warm water and ‘Milton’, (the sterilizing agent made up to the recommended dosage specified on the bottle), leave overnight then rinse out thoroughly.  If the problem persists, try filling the tank with water and charging with a  triple dose of Aqua Rinse.  Leave for 48 hours and flush through. Repeat until the residue build up subsides.

N.B.   Normally used to remove limescale build up or hard water stains,  please find attached a citric acid treatment which may be used as a final alternative should you find it necessary.

Since receiving this advice I have found 4 'Milton' tablets once a week has cured the problem long term. Another alternative solution is to use 'Washing Machine' cleaners found on any supermarket shelf.

Citric Acid Treatment
Fresh Water Tank - Algae Build Up Solution

Algae build up can be reduced by cleaning with 10% Citric Acid solution.
Citric Acid is a white granulate that can be obtained from any chemist.
Preparation Of the Solution:
Measure out 100 Grams of the Citric Acid to 900 Grams of Water and stir until dissolved.  Add a few drops of washing up liquid and stir again.
Make up enough solution to submerge the affected areas.

Pour the solution into the Fresh Water Tank and let it stand at least overnight or a full day.
Depending on the affected area it might be necessary to make up more liquid and repeat the treatment.

A recent letter to a motorhome magazine suggest pouring Half a bottle of orange juice into the tank, leave overnight, drive the vehicle to move the liquid about, and all is OK!

As I did not have the materials on our recent trip to France, I found that Milton Fluid, in tablet form, cured the problem. 4 tablets place after  every waste water drain down eliminated all smells during a hot month in the South of France.

Another alternative solution is to use 'Dish Washer Machine' cleaners found on any supermarket shelf.

Thetford Cassette Level Indicator

A common fault with the level indicator is; It stops indicating. This is due to the float loosing it's float insert, which is made from a light plastic material.

This drops into the cassette and is disposed of when you next empty the tank.

If you are aware of it, are able to retrieve it, then you can replace it inside the cassette, and glue it position.

This is a much better option. If you are not able to do this then a replacement is necessary. It took me 4 hours to do this job, because of my inexperience.

I would recommend a Caravan repair dealer to the work.

The missing float insert can be seen in the gap of the white mechanism, in the photo

Click for larger image

To replace the float mechanism is simply:

1. Take of the blade mechanism by unscrewing the top face screws.

2. Place your hand inside the cassette and wrench off the old float. Making a mental note how it is fitted by feeling it before removal.

3. Refit the new float mechanism.

No 3. is the hard part, as it's difficult to feel the location. That's my reason for the 4 hour job.

Information on the Thetford Toilet, and handbook in PDF format, can be found at their web site:


     Previous letters have touched on the problem of smells in the Motorhome. None that I can recall have mentioned toilet/washroom smells. Perhaps others have not had our problems, which we experienced in Spain this year.

     We are first timers to Motorhome ownership. We have never done any caravaning or owned a Motorhome before.

     Toilet smell was becoming an embarrassment, causing me to change the cassette and chemicals every other day. The usual shaking of the cassette with fresh water, after draining was not a solution. Until I noticed some continentals and their methods used.

     The solution was to add fresh water, then the fresh chemicals, slush from side to side. It's not advised being too vigorous while slushing, as you can loose the internal tank capacity float. Turn the cassette upside down, flap closed, and leave for a short time upside down. Any leakage when upside down is minimal, a few drops only, any thing larger then your seals need changing. By turning it upside down you are disinfecting the moving parts in the lid.

     This was our solution, no matter how hot the weather, our toilet always smelt fresh.

See Skyblue Camping & Outdoor Warehouse for toilet fluid information


Using Blue Diamond Toilet Fluid? 

Our toilet fluid is specially formulated to break down toilet waste effectively and to create a pleasant odour. Blue Diamond toilet fluid is extremely effective and has been made in Yorkshire for 21 years. The blue fluid is used in what is known as the bottom tank of the toilet.

Blue Diamond produce three types of toilet fluid. Our three litre toilet fluid is not a concentrated fluid and contains 10% formaldehyde, our 2 litre blue toilet fluid contains 24% toilet fluid, and so is classed as a concentrate, and our third type is a formaldehyde free formula, known as Toilet Fluid Green.

When using our 24% toilet fluid it is important to remember that you can use half as much as any other non-concentrated formula - so there's no need to throw as much down the toilet. Simply put 1/2 litre of fresh water into the toilet. Then add 50mls of Blue Diamond concentrated toilet fluid (or approx 100mls if using our non-concentrated 3 litre bottle).

Our green toilet fluid is concentrated, so like our blue toilet fluid, 50mls is fine for every 15 litre holding capacity of the waste tank. 50mls is approximately one egg cup full.

An average portable toilet has a waste tank of between 25 and 30 litres capacity, which means that around 100mls of fluid is fine, which is the same as about half a tea mug.

If you do notice any problems with the breakdown of waste please up the dosage in small measures. You should never expect to use as much as 200mls for a 30 litre waste tank.

We now use the 'Walex' sachets which are very effective up to the time when the cassette requires changing.


     For those who might be getting their Motorhome out of storage, as we are, you may find that the Thetford Toilet gives trouble. Intermittent or not flushing. 

     Turn off the toilet 12 Volt electrics before carrying out any repairs. 

     The solution is to remove the toilet holder in the toilet body, This container is a push fit and can be removed by easing the rim by small amounts around it's perimeter.  This then exposes the inside of the Thetford bench and the water immersed pump. 

     Remove the pump and check for any dirt obstacles which has stopped the pump impellers.  Rotate the the impellers by hand to ensure they are free. They can be found at the base of the pump body.

     Turn on the electrics and start the flush while holding the pump in your hand.  It's OK to do this for short bursts, but not recommended for long periods without it being immersed in water.  The water keeps it lubricated. 

     If after this the pump does not rotate, check the cables back to the fuse.  Check the fuse and ensure you have 12Volts at this point.  If you have, then you must consider the pump as being faulty.


Cassette C2 
Permanent, fixed bowl toilet for caravans and Motorhomes. This Cassette toilet has an integrated freshwater tank and features a powerful touch button electric flush.

Information on the Thetford Toilet, and handbook in PDF format, can be found at their web site:


Finish: white 
Flush: electric (12V) 
Integrated pour-out-spout: yes 
Separate toilet tissue storage compartment: yes [C4,NO]
Waste tank capacity: 20L 

Freshwater tank capacity: 15L 

Thetford Toilet Cassette Seal Fault

After a winter in storage, a few checks brought up this image as I prepared the cassette for use. The seal had taken on a ribbed effect.

This was replaced immediately.

This is easily done by removing the slide cover, then the eight screws, lift out the seal and replace with a new one in the same way the old one came out. Note the cut away rims on the top of the seal, they should be facing the longest sides of the cassette.

The ribbed effect would have meant toilet odours escaping around the ribs, and possibly allow splashing while the vehicle was travelling.

I have read that toilets should be left open during idle periods of the Motorhome, to stop the moveable place sticking! If the plate does stick in the open position then the cassette cannot be removed from the side door for maintenance. If it does stick in the closed position then maintenance can be carried out as shown below.

Thetford Toilet Cassette.

The sheen on the cassette aperture interior is due to the special Thetford protective spray.

Tools required for Seal change

Showing screws to remove.
Note the positions of moveable cover and the seal cover.

Remove slide cover and note position for reassembley.

Removed faulty seal, perished and ribbed

Remove screws.

New seal ready for fitting

Note the way the seal is positioned. Note the cut away ridge. Shown by the No 2 screwdriver. Must be fitted opposite the middle screw.

Place the seal cover. Note the yellow triangle is close to the ring valve

Replace screws. Do not screw too tight, just pinch screws. Any tighter and you strip the thread.

Old seal, note the ribbed edges!

Old seal removed. This seal caused the toilet to splash up into the interior on rough roads.

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