The Truth about Epsom Salt and Septic Safety 

We get asked this a lot, and the short answer is yes, Epsom salts are safe – as long as you use them in sensible quantities. But before we dive into the science, let’s step back and see where these humble salts came from.

A Farmer, a Spring, and the Birth of Epsom Salts

The story of Epsom salts starts in the early 1600s in the English town of Epsom, Surrey. A farmer, Henry Wicker, noticed his cattle refused to drink from a bitter-tasting spring. When the water was evaporated, crystals were left behind – what we now know as magnesium sulphate heptahydrate.

Word spread quickly, and soon “taking the waters” at Epsom became fashionable. By the Victorian era, spas all over England were serving up mineral-rich waters and baths, and Epsom salts were hailed as a cure for everything from digestive complaints to “melancholy.” A long, hot soak in Epsom salts wasn’t just a luxury; it was considered medicine. 

Fast-Forward to Today

These days, Epsom salts are more of a self-care staple than a medical prescription. You’ll find them in our bath soaks, foot baths, and even sprinkled in the garden to help tomatoes and roses thrive. Their enduring appeal lies in their simplicity: magnesium for tired muscles, sulphate for skin softness, and that timeless feeling of deep relaxation.

At BathCalm, we’ve taken this centuries-old ritual and elevated it with our Bath Meditation Soaks; pure Epsom salts blended with botanicals and essential oils, paired with guided meditations you can access by QR code. It’s the perfect way to transform your soak into a complete body-and-mind reset.

But what about when your home doesn’t run on mains sewerage? Are Epsom salts safe for septic tanks and biocycle systems? Let’s break it down.

Is Epsom Salt Harmful to Septic Bacteria?

There’s a common misconception that Epsom salts might kill off the bacteria in your septic tank. In reality, they’re completely harmless unless used in ridiculously huge quantities. If you want the science to back up this statement, you can find this study here.

Septic systems rely on bacteria to “digest” solids and break waste down into clean liquid that filters through to the soakage trench. There are three main types of bacteria in a septic tank:

• Aerobic bacteria need oxygen and do most of the heavy lifting in breaking down solids.
• Anaerobic bacteria don’t need oxygen and are more resistant to environmental changes.
• Faecal coliforms naturally present in human waste, some of which can contain pathogens.

In the correct amounts, Epsom salts don’t harm any of these bacteria, because they are not anti-bacterial.

Size Matters

Here’s the fun part: a typical bath holds around 200 litres of water. The concentration of Epsom salts that would start showing antibacterial effects is 2000 grams per litre.

That means you’d need 400 kilograms, yes, kilograms, of Epsom salts in your bathtub before it would upset your septic tank. To put that in perspective, that’s more than double what commercial float centres use in their tanks!

By comparison, BathCalm’s Bath Soaks recommend just 200 grams per bath about half a container or 400 grams for a two-person spa. That’s more than 2000 times lower than the levels that could cause an issue. In other words: perfectly safe.

What About Other Salts?

Not all salts are equal when it comes to septic health.

• Epsom salts (magnesium sulphate) are safe, pH neutral, and non-disruptive. It is not anti-bacterial.
• Pink Himalayan or sea salts (sodium chloride) on the other hand – not so safe. Chloride is a bacterial assassin, great for curing meat but terrible for the microbes in your septic tank. Sodium chloride can also damage soakage trenches by altering soil structure, making it harder for wastewater to filter.

So, while that pretty pink salt may look great in a jar, it’s not your friend if you’re on septic.

The Balance Factor

Healthy septic systems rely on the right pH balance (between 6.5 and 7.5). Epsom salts are naturally pH neutral, so they won’t disrupt this delicate environment. Yet another reason why they’re a safer choice than many alternatives.

History Meets Modern Comfort

It’s fascinating that something first discovered in a cow pasture ended up being bottled as medicine in Victorian spas, and today still finds its way into our bathrooms. The difference now is that we don’t need to worry whether it’s safe – because we know it is.

So go ahead, light a candle, run a bath, and add a generous handful of BathCalm’s Epsom Salt Meditation Soaks. You’ll be partaking in a tradition that’s centuries old, and you can do it guilt-free knowing your septic or biocycle system will be just fine.

Happy soaking!