How to Stop My Garden from Smelling Like Sewage

Few things can ruin the peace of a beautiful garden like the unmistakable smell of sewage. What should be your private sanctuary, a space for fresh air, gardening, barbecues, and relaxation, can quickly turn into a place you’d rather avoid. If you have noticed a foul, sulphurous smell outdoors – particularly after it rains – you are not alone. Many homeowners experience this issue, and it’s not just an inconvenience. A persistent sewage smell can signal that something is wrong with your drainage, septic system, or soil health.

This article explains what usually causes sewage smells in domestic gardens, why it’s not something to ignore, and how organic enzyme-based remediation – such as the solution developed by Bioglobe – can safely remove the odour at its source, without damaging the environment or harming your pets.

We will take you through three key sections:

• Problem – Common causes of sewage smells in gardens
• Consequences – How persistent sewage smells affect your health, soil, pets, and property
• Solution – How Bioglobe’s bespoke organic enzyme remediation works, and why it is a safe and effective choice

Finally, we’ll answer the most common questions people ask about this problem, so you know what to expect when tackling it.

Problem – Why Does My Garden Smell Like Sewage?

The smell of sewage outdoors is usually caused by the escape of wastewater, untreated sewage, or decomposing organic matter close to the surface. But that broad explanation hides several possible sources. To effectively solve the problem, it’s helpful to understand the most common scenarios.

1. Broken or Leaking Drains

One of the most frequent causes of sewage smells is a damaged drainpipe. Your property’s waste pipes run underground and connect to the public sewer or a septic system. Over time, these pipes can crack due to soil movement, root intrusion, wear and tear, or ground subsidence. Even a small crack can allow wastewater to seep into the soil.

When wastewater escapes, bacteria in the soil begin to break it down, producing gases such as hydrogen sulphide, methane, and ammonia – all of which have strong, unpleasant odours. Because these gases are lighter than air, they rise to the surface and escape through the soil, creating the characteristic smell of sewage.

2. Septic Tank or Soakaway Problems

If your property is not connected to the mains sewer and relies on a septic tank or a private sewage treatment plant, a problem with the system could be responsible. Septic tanks need regular emptying to remove accumulated sludge. If this is neglected, or if the soakaway field becomes saturated, untreated effluent may overflow into the surrounding soil.

An overfull or damaged septic tank can create a persistent smell that becomes worse after rainfall, as the surrounding ground struggles to absorb more liquid.

3. Wastewater Run-Off After Rain

Sometimes the problem isn’t coming from your own property at all. Heavy rain can wash waste from blocked drains, combined sewer overflows, or neighbouring properties into your garden. Surface water mixed with wastewater can pool in low areas or soak into your soil, where it begins to decompose.

This is why many people notice that the smell is particularly strong after rain – the added moisture brings odorous gases to the surface and spreads the contamination.

4. Blocked or Stagnant Drains

Even if your pipes aren’t broken, a blockage can still create a foul smell. When waste gets trapped, it can go anaerobic – meaning it decomposes without oxygen. This process produces a range of foul-smelling gases. If the blockage is underground and near the garden area, those gases may escape through inspection chambers or even through the soil.

5. Natural Organic Decomposition

Not every bad smell is caused by human waste. Decaying leaves, dead rodents, or buried food scraps can all produce strong smells that mimic sewage. In warm weather or waterlogged conditions, the decomposition process is faster and the smell stronger. While this might be less dangerous than actual sewage contamination, it still indicates an imbalance in your soil ecosystem.

Consequences – Why You Should Act Quickly

While it can be tempting to ignore the smell and hope it goes away, persistent sewage odours are a sign of a deeper issue that should not be overlooked. Here’s why.

Risk to Human Health

Sewage gases contain hydrogen sulphide, ammonia, methane, and other volatile organic compounds. At low levels, these can irritate the nose, eyes, and throat, causing headaches, dizziness, and nausea. At higher levels, hydrogen sulphide can be dangerous, even life-threatening.

In addition to gases, sewage contains pathogens such as E. coli, Salmonella, and viruses. These can pose a risk if they contaminate soil where children play or where you grow vegetables. Even indirect contact – such as a dog walking through contaminated mud and bringing it into the house – can spread germs.

Harm to Pets and Wildlife

Dogs and cats are naturally curious. They may sniff, dig, or even drink from contaminated puddles. This can expose them to parasites, bacteria, and toxic compounds. Wildlife such as hedgehogs, birds, and pollinating insects can also be harmed if the contamination spreads through the garden.

Soil and Plant Damage

Persistent contamination can alter the chemistry of your soil. Anaerobic conditions (where oxygen is depleted) harm plant roots and beneficial microbes. This can cause patchy grass, yellowing leaves, and poor plant growth. In vegetable gardens, the risk is higher because edible crops could be exposed to harmful bacteria.

Long-Term Property Damage

A leaking pipe won’t fix itself. If left untreated, the leak may worsen, washing away soil and undermining patios, driveways, or even house foundations. The longer the problem persists, the more expensive the eventual repair may be.

Loss of Enjoyment and Property Value

Perhaps most obviously, a garden that smells of sewage is not pleasant to spend time in. You may find yourself avoiding barbecues, outdoor dining, or simply sitting outside. If you plan to sell your home, a foul smell could put buyers off and lower the property value.

Solution – How Bioglobe’s Organic Enzyme Remediation Can Help

The good news is that you do not have to live with this problem. Traditional solutions often involve digging up large sections of the garden to locate leaks or flushing chemicals through the soil to mask the smell. These approaches can be costly, disruptive, and environmentally harmful.

Bioglobe takes a different approach: organic enzyme remediation.

What Is Enzyme Remediation?

Enzymes are natural catalysts – proteins that speed up chemical reactions. In the context of sewage contamination, specially selected enzymes can break down fats, proteins, and carbohydrates in the waste, converting them into simple, harmless molecules such as water and carbon dioxide.

When applied to contaminated soil or drains, enzyme solutions work at the molecular level to digest the organic matter causing the smell. This is not a masking agent – it removes the source of the problem.

Why Bioglobe’s Solution Is Different

Bioglobe’s laboratory in Cyprus is dedicated to developing and optimising enzyme blends for environmental remediation. When presented with a sewage smell problem, Bioglobe can:

• Analyse the contamination – testing samples to determine what pollutants are present
• Formulate a bespoke enzyme solution – tailored to the specific type of waste and soil conditions
• Apply the treatment safely – ensuring that it targets the problem without harming plants, pets, or beneficial soil microbes

This is particularly useful when the source of the leak is unknown. Enzymes can travel through the soil and reach areas you cannot easily dig up, breaking down contaminants in situ.

Advantages of Enzyme Remediation

• Eco-friendly – no harsh chemicals, no risk of groundwater contamination
• Safe for pets, children, and wildlife – enzymes are biodegradable and non-toxic
• Non-disruptive – no need to excavate the entire garden
• Cost-effective – targeted treatments save money compared to major pipe replacement
• Long-term effect – removes the organic source of odour rather than just masking it

What to Expect

After the enzyme solution is applied, most people notice a reduction in smell within a few days. Depending on the severity of contamination, full remediation may take several weeks, during which Bioglobe can monitor progress and adjust treatment if needed.

Once the contamination is dealt with, follow-up maintenance treatments can be used periodically to keep drains clear and prevent future problems.

FAQs

Why does my garden smell like sewage after rain?
Rainfall can flush contaminants closer to the surface, where odorous gases escape more easily. It can also bring wastewater run-off from nearby drains or neighbouring properties into your garden, temporarily increasing the level of contamination.

Are sewage smells harmful to breathe in?
Yes. While low levels are mostly just unpleasant, prolonged exposure can irritate the respiratory system and cause headaches or nausea. In high concentrations, some gases like hydrogen sulphide can be hazardous.

Will enzyme treatments get rid of the smell permanently?
Yes, provided the underlying source of contamination is dealt with. Enzymes break down the organic matter causing the smell, so once the waste is fully digested and leaks are repaired, the smell should not return.

Can enzymes work if I don’t know exactly where the leak is?
Yes. Because enzyme solutions move through soil and water, they can reach areas you cannot see or access, breaking down waste even if the exact leak point is unknown.

How long before the smell goes away?
This depends on the extent of contamination and the weather conditions. Many homeowners notice a significant reduction within 24 to 72 hours, with full odour removal achieved within a few weeks for heavier contamination.

Bioglobe offer Organic Enzyme pollution remediation for major oil-spills, oceans and coastal waters, marinas and inland water, sewage and nitrate remediation and agriculture and brown-field sites, throughout the UK and Europe.

We have created our own Enzyme based bioremediation in our own laboratory in Cyprus and we are able to create bespoke variants for maximum efficacy.

Our team are able to identify the pollution, we then assess the problem, conduct site tests and send samples to our lab where we can create a bespoke variant, we then conduct a pilot test and proceed from there.

Our Enzyme solutions are available around the world, remediation pollution organically without any harm to the ecosystem.

For further information:
BioGlobe LTD (UK),
Phone: +44(0) 116 4736303| Email: info@bioglobe.co.uk