It is one of the questions we are asked most often.
Whether you are using traditional Marseille Soap Flakes for laundry, Savon Noir for household cleaning or a simple Marseille Soap bar for everyday jobs around the home, many customers want to know the same thing: will it affect my septic tank?
The short answer is no. In fact, if you have a septic tank, traditional soap is one of the products we would particularly recommend.
Marseille Soap and Savon Noir are readily biodegradable soaps made from saponified vegetable oils and have been used for generations for washing and cleaning in France, where septic tanks and other forms of private drainage are commonplace. The French manufacturers we work with recommend them for septic systems, and it is one of the reasons they make such good sense for customers with private drainage here in the UK too.
A septic tank relies on naturally occurring microorganisms to break down waste, so regularly pouring large quantities of bleach, strong disinfectants and aggressive drain cleaners into it isn't a particularly good idea. Normal household cleaning is rather less complicated, and most of it can be done with soap.
Savon Noir and Marseille Soap for household cleaning
Savon Noir is one of the products we recommend most often. Traditionally made from saponified vegetable oils, usually olive oil, it can be diluted for floors, tiles, worktops, cupboards and general household cleaning, while also being particularly good at cutting through grease and accumulated grime. A little goes a long way, which is another advantage when everything you use ultimately ends up in your own drainage system.
A traditional Marseille Soap bar is equally useful for smaller cleaning jobs. Work a damp cloth or brush across the soap and use it for sinks, worktops, greasy marks and countless other jobs around the house. Soap removes grease and dirt so that it can be rinsed away, which is all that most everyday cleaning actually requires.
We recently had a customer who had moved into a very dirty property and was trying to work out what to give her cleaner, who was adamant that she needed bleach. For the kitchen, cupboards and general cleaning we suggested soap; for the harder deposits in the bathroom, citric acid; and for staining and jobs that needed a bleaching action, sodium percarbonate.
Citric acid is particularly good for limescale and mineral deposits around taps, shower heads, shower screens, sinks and toilets. Sodium percarbonate has a different job: dissolved in water it releases hydrogen peroxide and sodium carbonate, giving an oxygen-based bleaching and stain-removing action which is useful for some of the tougher jobs around the home as well as laundry.
Between those three — soap, citric acid and sodium percarbonate — you can clean almost everything around the home.
When would you actually use bleach?
For most household cleaning, we wouldn't. Soap will remove everyday dirt and grease, citric acid is far better for limescale, and sodium percarbonate gives us an oxygen-based bleaching action for stains and whitening. None of those jobs needs chlorine bleach simply because the surface is particularly dirty.
Bleach is only relevant when disinfection is genuinely the job, rather than cleaning: for example, after sewage contamination, certain infectious illnesses in your home, or where specific hygiene guidance calls for a chlorine-based disinfectant. Those are relatively unusual situations in an ordinary household, which is why bleach doesn't form part of our everyday cleaning cupboard.
If you have a septic tank, occasional use when it is genuinely needed shouldn't be a concern; it is repeated or excessive use of strong disinfectants that you want to avoid. And if you do use bleach, never mix it with other cleaning products, particularly acids such as citric acid or vinegar.
Marseille Soap Flakes for laundry
Traditional Marseille Soap Flakes are particularly well suited to laundry in homes with septic tanks. They are the same traditional soap in flake form, made from saponified vegetable oils, readily biodegradable and recommended by our French manufacturers for use with septic systems.
As with any laundry product, there is no advantage in using more than you need. Our instructions make a relatively thin soap-flake laundry liquid, and the amount used for each wash can then be adjusted for the size of the load, how dirty it is and your water hardness. More soap doesn't automatically mean cleaner washing and, particularly in hard-water areas, too much can make rinsing more difficult.
We occasionally see claims that soap flakes will put fats and oils into your washing machine or drainage system because they are made from vegetable oils. The oils are the raw materials used to make the soap; during saponification they react with the alkali and are converted into soap. Olive-oil Marseille Soap Flakes no more put olive oil into your washing machine than an olive-oil soap bar covers your hands in olive oil.
For customers who contact us because they have a septic tank and want to rethink their laundry products, Marseille Soap Flakes are the first things we suggest.
Do I need to buy products labelled ‘septic safe’?
There is no single UK certification that gives household cleaning products an official ‘septic safe’ status, so you don't need to replace everything in the cleaning cupboard with products carrying those words on the label.
We prefer to know what we're using. Marseille Soap and Savon Noir are readily biodegradable traditional soaps and the French manufacturers who make them recommend them for septic systems. Citric acid deals with limescale, sodium percarbonate gives us oxygen-based bleaching and stain removal, and between them they cover most of the cleaning we need to do.
There are also some fairly obvious things that don't belong in a septic system. Cooking fats and oils shouldn't be poured down the sink, wipes and sanitary products shouldn't be flushed, and solvents, paints and other unsuitable chemicals need to be disposed of properly rather than washed down the drain. Your tank also needs to be emptied and maintained according to the requirements of your particular system.
None of that requires a specialist cleaning cupboard. If anything, we find a septic tank is a very good reason to simplify one.
For everyday household cleaning we'd choose Savon Noir and Marseille Soap; for laundry, Marseille Soap Flakes; for limescale, citric acid; and for staining and oxygen bleaching, sodium percarbonate. Between them, that's an enormous amount of the cleaning in an ordinary home covered by four traditional, straightforward products.
Traditional Marseille Soap and Savon Noir have been used for washing and cleaning in French homes for generations, including those relying on private drainage. They're simple, readily biodegradable and remarkably versatile, which is exactly why we recommend them so confidently to our customers with septic tanks.