Napisan and Look-Alikes safe for Septic Tanks – a professor’s view

by Collyn Rivers and Professor Ian Jenkins

Napisan is safe for septic tanks

That Napisan and Look-Alikes are safe for septic tanks is definitively confirmed.

The labelling of Napisan and many Look-Alikes (e.g. Nappy Treatment Plus, Ultra Booster Everyday Plus Laundry Soaker, Laundry Soaker and Booster etc) is clear.

All state these products are safe for you to use in septic tanks. Products can be bought from supermarkets worldwide. It is also easy to make your own Napisan Look-Alike. You can do so from readily bought material.

This paper is provided by Professor Ian Jenkins. He is a retired Professor of Chemistry (and now Professor Emeritus at Griffith University). Professor Jenkins states this: ‘In my opinion, sodium percarbonate is probably the cheapest, safest, and most effective product to use in portable toilets, provided it is used as directed’.

Professor Jenkins’ paper

Thirty years ago, the active ingredient of Napisan was potassium monopersulfate (KHSO₅). This oxidises sodium chloride to sodium hypochlorite, i.e., bleach. [H. Gaya et al, J. Hyg., Camb. 1979, 82, 463].

Sodium hypochlorite can wreck septic tanks. About twelve years ago, the main bleaching agent used was sodium perborate (NaBO₃). This is a milder reagent than chlorine bleach. It is relatively non-toxic. Nevertheless, concerns over sodium perborate’s boron content led to it being replaced.

That replacement was sodium percarbonate.  [M. McCoy, Chemical and Engineering News, 2003, Volume 81, Number 3, p. 17].

Today, Napisan contains sodium carbonate (30-60%). Sodium percarbonate (10-30%) and sodium sulfate (10-30%). It has small quantities of surfactants.  ‘Look-alikes’ appear to be similar.

Sodium percarbonate is the active ingredient in all. It is made by mixing sodium carbonate (washing soda) with hydrogen peroxide.  When dissolved in water, it forms sodium carbonate and hydrogen peroxide.

Hydrogen peroxide oxidises smelly compounds. These include hydrogen sulfide, methanethiol, dimethyl sulfide. It also oxidises nitrogen-containing compounds such as skatole. Furthermore, Skatole is found in human waste.

In the absence of organic material, hydrogen peroxide decomposes slowly. It becomes oxygen and water. Your portable toilet’s content has little hydrogen peroxide. Furthermore, it should have negligible effect on septic systems.

Sodium percarbonate is often used in eco-friendly cleaning products. It is the active ingredient of Odour-B-Gone. The surfactants in some Napisan look-alikes are biodegradable. Check the label to enable you to confirm this.

Sodium carbonate (washing soda) and sodium sulfate (Glauber’s salt) are naturally occurring chemicals. They are relatively non-toxic. You’d need to swallow a great deal to kill you.

Environmentally safe

Hydrogen peroxide is an environmentally safe antimicrobial agent. It is produced naturally in the human body. It is produced in biological systems generally. However, too much can be harmful for you. As Paracelsus noted 500 years ago: “All substances are poisons; there is none that is not. The right dose differentiates between a poison and a remedy”.

Sodium percarbonate nappy and laundry products will cost you $2.50-$4.00/kg. All contain between 280 and 346 grams per kg of sodium percarbonate. Moreover, most are claimed safe for septic tanks. They will give you excellent results.

Take care when buying

When purchasing Napisan or Napisan look-alikes, ensure you read the label carefully. Supermarkets may change product names. Furthermore, the contents are often shown in tiny print. Look for the amount of sodium percarbonate. That greater than 300 g/kg is best. Moreover, some state, ‘safe for septic tanks’.

Pure (100%) sodium percarbonate is preferable. Few supermarkets sell it. Brewing suppliers, however, sell sodium percarbonate (100%). The typically charge you about $6 a kilo.

To use, add two level tablespoons of sodium percarbonate to one litre of water. Stir for a few minutes. Then pour it into the lower tank of the portable toilet (assuming 20 litre capacity). Wash any undissolved powder into the tank with a further one litre of water. Furthermore, dissolve 1 level tablespoon of sodium percarbonate (per 9 litres) in that flush tank.

As with all chemicals, ensure you keep sodium percarbonate out of your children’s reach. Moreover, avoid contact with your skin, and your eyes in particular. Furthermore, never mix other chemicals with it. See also: https://rvbooks.com.au/safe-toilet-chemicals-2/