In the UK, it is generally not advised to flush dog or cat poo down the toilet. Pet waste can contain parasites, bacteria and veterinary medicine residues that our sewage systems are not specifically designed to handle.

The topic of flushing pet poo is a rather murky one - in every possible sense. The answer can vary depending on where you live, what your local water company says, and whether you are talking about dog poo, cat poo, litter, or so-called “flushable” poo bags.

But as a general rule, most UK water companies advise that toilets should only be used for the three Ps: pee, poo and paper - and by “poo”, they usually mean human poo.

Pet poo is different. It can carry different pathogens, parasites and chemical residues, including some flea, tick and worming treatments. That makes flushing it less simple than it might seem.

Key takeaways

• Flushing dog or cat poo down the toilet is not advised.
• Do not flush cat litter, even if it is labelled “flushable”, biodegradable or compostable.
• Do not flush biodegradable, compostable or “flushable” poo bags.
• Pet waste can contain parasites, harmful bacteria and veterinary medicine residues.
• Some anti-parasitic drugs can be excreted in pet faeces and can enter our environment this way.
• If you are seriously considering flushing pet poo, ask your local water company first.

 

Can you flush cat poo down the toilet?

No, you should not flush cat poo down the toilet.

Cat poo can contain pathogens, including a parasite called Toxoplasma gondii, which can infect people and animals. Toxoplasma is particularly concerning because it is highly resistant and may not be reliably removed by all municipal wastewater treatment systems. 

Wastewater systems are designed primarily around human waste. They are not necessarily designed to deal with every parasite or pathogen found in pet waste.

So the safer advice is simple: do not flush cat poo.

 

Can you flush cat litter?

No. You should not flush cat litter, even if the packaging says it is biodegradable, compostable or flushable.

Cat litter can cause plumbing and sewer blockages. It may also carry the same parasite risks as cat poo, especially Toxoplasma.

Even “flushable” cat litter can be a problem because toilets and sewers are not designed to handle litter material. The fact that something can physically disappear down the toilet does not mean it belongs in the wastewater system.

 

Can you flush biodegradable or flushable poo bags?

No. You should not flush biodegradable, compostable or “flushable” poo bags down the toilet.

Many biodegradable and compostable products are designed to break down under specific composting conditions, not in cold toilet water or sewer pipes.

That means they may not disintegrate quickly enough after flushing. Instead, they can contribute to blockages in household plumbing, sewer pipes and wastewater systems.

The same applies to “flushable” poo bags. Even if a product claims to be flushable, it is worth being very cautious. In fact, 'flushable' poo bags have historically caused $8 million in blockages in Australia so it's not recommended to try flushing these bags, despite what they claim!

 

What about flushing dog poo without the bag?

Flushing dog poo without the bag might sound more reasonable, but it is still generally not recommended.

Dog poo is not the same as human poo. It can contain pathogens that are different from those typically found in human waste, including parasites, bacteria and viruses with zoonotic potential - meaning they can potentially infect people.

One important parasite is Toxocara, a roundworm that can be found in dog faeces. Toxocara eggs are highly resilient and can survive harsh conditions.

Toxocara can also infect humans. In rare cases, infection can affect the eyes and cause serious disease, especially in children.

This is one reason some wastewater companies advise against flushing animal faeces: the system is not designed with these additional pet waste risks in mind.

 

What about flea, tick and worming treatments in pet poo?

This is an important and often overlooked issue.

Many pets are treated with anti-parasitic medicines, including flea, tick and worming treatments. Some of these drugs, including certain isoxazoline treatments, can be excreted in faeces, sometimes in active form. 

That matters because flushing pet poo could introduce these drug residues into the wider wastewater system.

Wastewater treatment is good at many things, but it is not designed to remove every veterinary medicine residue. Some medicines and chemical residues may pass through treatment processes and enter rivers, streams or other waterways. 

This is particularly concerning because some anti-parasitic drugs are designed to kill invertebrates, which will cause significant ecological damage.

There is still a lot we do not know about what happens to these drugs once they enter waste systems, compost, soil or waterways. But that uncertainty is exactly why caution is sensible.

 

Could flushing pet poo harm aquatic life?

Potentially, yes.

Pet poo can introduce both biological and chemical risks into wastewater systems.

The biological risks include parasites and pathogens. The chemical risks include veterinary medicine residues, such as flea, tick and worming treatments.

Some veterinary medicines are highly toxic to aquatic invertebrates and insects. If drug residues pass through wastewater treatment unchanged, they could contribute to wider ecological damage.

 

Could flushing pet waste ever become a widespread solution?

Possibly, but not without major system changes.

In theory, flushing pet poo could seem convenient. It keeps waste out of bins and avoids using a bag. But for it to become a safe widespread solution, wastewater systems would need to be able to handle the extra volume, pathogen risk and veterinary drug residues.

The UK has millions of dogs and cats. If every owner started flushing pet poo, that would add a significant extra load to wastewater infrastructure.

The risk is not just “more poo in pipes”. It is more pet-specific pathogens, parasites and pharmaceutical residues entering a system that was not designed around them.

For flushing pet waste to become a responsible mainstream solution, we would likely need:

• Clear guidance from water companies
• Treatment systems designed to handle pet pathogens
• Better understanding of veterinary medicine residues
• Evidence that aquatic ecosystems would not be harmed
• Infrastructure capable of handling the extra waste

At present, we are not there.

Water management companies we contacted as part of our research emphasised that only the three P's - (human) Poo, Paper and Pee should ever be flushed down the toilet. 

 

What poo bags should you use?

If you dispose of your dog’s waste in general waste or dog poo bins, the goal is to pick up after your dog while minimising unnecessary environmental impact.

One option is to reuse suitable non-recyclable plastic packaging you already have at home. If that is not practical, poo bags made from recycled or waste materials can be a more realistic everyday option than bags made from virgin materials.

That is the idea behind our ReSEAcled Poo Bags.

They are made of existing waste and also directly fight ocean plastic pollution.

Experts advise that it's better to re-use waste that was already destined for landfill or incineration rather than virgin materials to make poo bags.

This helps reduce new plastic production and pollution, cuts carbon emissions and minimises energy use.