What Are The Right Bulking Materials For Dry Toilets And Composters

Dry and composting toilets are becoming increasingly popular across the UK, especially in off-grid homes, glamping sites, and eco-conscious properties. One key component to making these systems work efficiently is the bulking material you use. While many people turn to sawdust or wood chippings, there are good reasons to opt for a bulking material specifically designed for dry toilets and composters – and just as importantly, why it should be peat-free.

In this blog, we’ll explore what bulking material does, why the right choice matters, and why avoiding peat is essential for sustainability.

What Is Bulking Material?

Bulking material is added to composting toilets and dry toilets after each use. Its main job is to:

• Absorb excess moisture from solid waste and urine
• Create airflow within the compost pile to encourage aerobic decomposition
• Suppress odours
• Support microbial activity that helps break down waste

In a nutshell, bulking material ensures the composting process works efficiently and hygienically. Without it, your toilet could become smelly, overly wet, or even anaerobic (no air flow) – leading to a build-up of unpleasant gases and slow decomposition.

Sawdust and Wood Chippings: A Common (but Imperfect) Choice

For years, sawdust and wood chippings have been the go-to bulking material for dry toilets. They're natural, widely available, and affordable – often a by-product from workshops, sawmills or landscaping projects.

But while they can work, they’re not always the best option.

The Drawbacks of Standard Sawdust and Chippings:

1. Moisture Absorption Can Be Inconsistent
       Not all sawdust is the same. Fine sawdust might absorb too much moisture  and create a heavy, compacted mass which can become smelly, while coarse shavings might not absorb enough. This can throw off the balance of your toilet system.
2. Risk of Compaction
       If the sawdust is too fine or damp, it can compact and reduce airflow – leading to anaerobic conditions, slow decomposition, and bad smells.
3. May Contain Contaminants
       DIY or workshop sawdust may contain chemicals, adhesives, paint residues,     or treated wood particles – none of which are suitable for composting or     environmentally friendly disposal and could seriously upset the balance of     your compost.
4. Chippings Can Be Too Chunky
       Wood chippings might be too large and won’t provide the coverage or absorption needed after each toilet use. They also decompose more slowly than finer materials.

Why Purpose-Made Bulking Material Is Better

A bulking material specifically designed for dryand composting toilets – such as Biolan’s composting bulking material –is formulated to deliver optimal performance:

• Ideal particle size for airflow and absorption
• Balanced carbon content to aid decomposition
• Free from contaminants
• Easy to handle and store
• Formulated for year-round use

Specialist bulking agents often include a mix of natural fibres, untreated plant matter, and coarser organic particles. They createa structure within the compost that prevents compaction, keeps things aerobic, and helps prevent odours far more effectively than standard sawdust or chippings.

If you’re investing in a composting or dry toilet,it’s well worth using the right materials to keep it working at its best.

Why Peat-Free Is Essential

Many traditional composting products – including some bulking materials – contain peat. While it’s long been used ingardening and composting due to its absorbency and carbon content, peat is now known to be environmentally damaging.

The Environmental Cost of Peat:

• Peatlands are carbon sinks – They store more carbon than forests, and digging them up releases greenhouse gases into the atmosphere.
• Habitat destruction – Peat bogs are home to unique ecosystems. Harvesting peat destroys these delicate habitats.
• Takes centuries to regenerate – Peat forms at an incredibly slow rate, making it a non-renewable resource on a human timescale.

In the UK, government policy is already shifting towards banning peat in consumer products – especially for homegardening – and many sustainable suppliers have already gone peat-free.

When choosing a bulking material for your toilet orcomposter, peat-free options are the most ethical and future-proof choice.