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Help on toilet chemicals and disposing of toilet waste

Article by Peter Smith - Caravans Plus

We have an article that describes features to look for in Portable Toilets

We also describe the differences in Built-in Cassette Toilets

Do I need toilet additives and which are best?

It is possible to use a portable toilet for just overnight use without any chemicals at all. This can be useful if you need to empty contents into a composting type toilet where chemicals are prohibited. Any longer than one nights use or if used for more than a wee, then yes you will need an additive especially to rinse out.

Which additives are best for the environment?

There is not a black and white answer for this question. There are definite options available depending on your preference and depending on where you will be disposing of the waste.

Toilet additives can come in very ECO-friendly versions or others that are not so friendly but have other benefits. More on this after we look at where you can empty your toilet waste which is also described as Black Water.

Where will I empty my toilet waste?

Many first time users worry about disposing of the waste, but it can be quite easy and hygienic. Most modern holding tanks can be carried with just one hand and feature large non-splashing dump spouts and venting buttons. It is certainly less effort than a number of trips to the communal loo, plus you can have your own soft loo paper, even with a print if you fancy.

The biggest area of concern when disposing of toilet waste is if the additives (sounds better than chemicals) will effect the toilet system that they are added to. This can be confusing because there are a number of completely different toilet systems and lot of different opinions.

Finding Dump Points

Unless you want to dig a hole, 50m away from any water course, you should look at the more sustainable options. Look for these blue signs while traveling or check out these smart phone apps that will locate your nearest dump point.

How to find a dump point

Try WikiCamps (my favorite) or Caravan Helper: Find Dump Points. These will find a Dump Point close to you on a map.

If you will be emptying your waste tank into a dump point connected to a sewer system you can use any of the toilet additives available from CaravansPlus.

Using Dump Points

Tips on using dump points

Dump Points are becoming more and more widespread in Australia as a free service to the RV public. Many caravan parks also provide them for their customers, or for others for a small fee.

These Dump points can be used for portable toilets, cassette toilets and also RV's that contain built-in holding tanks that empty via a hose.

These should always be rinsed after use and left with the lid closed. Take care not to drop your dump cap but if you do, we can help out with any spares.

Using Amenity Blocks

While some caravan parks may permit you to empty the waste contents into their toilets, this is certainly frowned upon by some caravan parks and by other amenities users. Any septic safe additive will not be a problem if they are disposed of in flushable loo's.

Using Pit Toilets

The disposal of waste that includes sodium per-carbonate, as detailed below, in the standard concentrations is fine. You may use Septic Safe additives, BUT they must be used in the correct concentrations and have sufficient liquid at time of disposal. Pouring in a bottle of undiluted septic safe additive into a pit toilet is too concentrated and will have an adverse effect on the breakdown of the waste in often dry pit toilets.

Using Composting Toilets

This is a definite no-no. While the emptying of any waste is forbidden, it is the chemicals that are really the problem.

Types of Additives

Anything that is added to the flush tank or waste tank is classed as an additive, how bio-degradable or effective it is, is another thing altogether.

Generic Additives

Sodium per-carbonate is an effective chemical that is found in a number of brands of Laundry soaker's. The strength varies from 25% to 35% which is ample. 100% is available for sterilizing purposes from specialty suppliers but can cause too rapid a reaction in a waste tank. The following images show a selection of Laundry soaker's that would all work well.

Sodium Percarbonate powders

A small problem with these is the need to continually add a small top-up to the waste tank, as the chemical conversion to oxygen, water and sodium carbonate is quite rapid. Some commercial toilet products use the same chemicals but at a slower release rate. Odour-B-Gone is a tablet example of these commercial toilet products.

Both these options provide an eco-friendly solution, without any added fragrance. A combination of both may give a more balanced result over a number of days using a half tablet for slow release but boosted when required with a teaspoon of the less expensive laundry soaker. The addition of the laundry soaker to the flush tank is NOT recommended as it starts its chemical reaction as soon as it gets wet.

Where a toilet is used only for urine the above will have no effect. In this case we recommend the addition of a dash of white vinegar.

Flush tank additives

While all portable toilets have a separate flush tank, some built-in cassette or holding tank toilets use the main RV water tank to supply the water for flushing, so an additive cannot be used.

A spray bottle filled with the additive can be used, or Thetford produce a pre-packaged spray for this purpose.

Thetford Aqua Rinse Spray Bottle 500ml - Suit Toilets Without Flush Tank

Thetford Aqua Rinse Spray Bottle 500ml - Suit Toilets Without Flush Tank

31 In Stock Now.

Where an additive is placed in the flush tank, its purpose can be one or more of the following:

In addition to the above, it should be septic safe.

Thetford Aqua Rinse Concentrate - Flush Tank Additive- 750ml

Thetford Aqua Rinse Concentrate - Flush Tank Additive- 750ml

25 In Stock Now.

Waste tank additives

Environmentally sound waste tank toilet additives should be a major consideration. There are still toilet chemicals available in the market that we do NOT recommend. These contain formaldehyde which is toxic to the environment. CaravansPlus does NOT sell any chemical that contains formaldehyde.

Septic Safe

Any camper or caravaner who is interested enough to visit a National Park should also be concerned enough to look after the facilities provided.

In the rare locations where National or State Parks provide flushing toilets, these are usually the Septic style. There are a number of additives that are classed as Septic Safe and will not damage the bacteria that make the septic systems operate. These products will always state they are Septic Safe. Any specific toilet waste additive that does not state it is Septic Safe, should not be disposed of into a septic system. Some may say Eco-friendly or Boo-degradable but at CaravansPlus unless they specifically say Septic safe we advise to be wary.

As a general rule GREEN additives are the most environmentally friendly. Generally BLUE additives are a chemical that inhibit bacterial growth and mask the odor. If we had to give a simple recommendation that looks at conventions rather than regulations we would say use GREEN if you will use Septic systems at any stage, or BLUE if you will only use Dump Points.

You can always prolong your stay in a National or State park by having a spare waste tank. You would need to use a waste tank additive until you find a suitable dump point.

Liquid, Sachets, Tablets or Napisan

It does come down to personal choice on the method of including your additive.

The liquids require no additional dissolving, however they still need some flushed water to correctly circulate the additive. Getting the correct measure can be a bit of a guess unless you have a measuring cup or use one of the brands that includes measuring marks on the bottles.

Thetford Aqua Kem Green Concentrate - Waste Cassette Tank Additive - 750ml - Septic Safe

Thetford Aqua Kem Green Concentrate - Waste Cassette Tank Additive - 750ml - Septic Safe

12 In Stock Now.

Sachets are per-measured and also require some flush water to properly dissolve. Very easy to use.

Walex Bio-Pak Express Green - Waste Cassette Drop-In - 15 Sachets - Septic SafeSpecial Price

Walex Bio-Pak Express Green - Waste Cassette Drop-In - 15 Sachets - Septic Safe

356 In Stock Now.

Tablets will slowly dissolve and a little testing maybe required to find what works best for you. However they are very environmentally friendly.

Odour-B-Gone Enviro Friendly Waste Cassette Tablets - 20 Fast Action Tablets - Septic Safe

Odour-B-Gone Enviro Friendly Waste Cassette Tablets - 20 Fast Action Tablets - Septic Safe

9 In Stock Now.

The granular laundry soaker available from supermarkets are measured into the waste tank, and then supplemented with a small dose at each use. If slide value seals become less flexible they are readily replaceable on most brand name toilets.

Toilet Tissue

Is it necessary to use special toilet paper in a chemical toilet? Yes and no. It is certainly possible to use normal toilet paper in a chemical toilet, however there is a marked difference in time taken for the toilet tissue to dissolve.

Where a straight thru slide valve is used like in the portable toilets, this will have little effect. The problems mostly occur with the cassette waste tanks that have a mechanism within the tank. These moving parts are susceptible to fouling from the toilet tissue that does not dissolve properly. There is a good little You Tube video that shows the difference in the product shown below.

Thetford Aqua Soft Toilet Tissue - 6 Pack

Thetford Aqua Soft Toilet Tissue - 6 Pack

26 In Stock Now.

If you do use normal paper, like I have in the past, keep the cassette level while taking it to a disposal point. This will keep the mechanism clear.

Cassette Tank Cleaner

This is recommended for use at least once a year. It easily removes stubborn calcium deposits that can form on the inside of the waste tank or cassette. It is easy to use and scrubbing is not required.

Thetford Cassette Tank Cleaner - 1 Litre

Thetford Cassette Tank Cleaner - 1 Litre

60 In Stock Now.

To view our full range of toilet chemicals click below

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  • comment-avatar


    Hi, in the section discussing sodium per carbonate you mention it isn't any good if the toilet is being used only for urine and then add: "Where a toilet is used only for urine the above will have no effect. In this case we recommend the addition of a dash of white vinegar." I'm wondering... do you mean adding some white vinegar to the cassette tank where you already have added the laundry soaker - or are you talking about adding some white vinegar to the flush tank of the loo? IS it right to think that 'commercial' packaged sachets have additives that handle both #1 and #2? Thank you for your informative articles!!!!!

  • comment-avatar

    Lyn Bradley

    Hi. We have a small Mobil home which when we go visiting family and friends we stay in the van parked inside the yard. My question is. Is it safe to dispose of toilet waste down the household drain, as the nearest waste dump is quiet some kilometres away.

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