How long does it take to get rid of the septic tank smell outside?

With CleanWaste, most customers notice a significant improvement within 1–2 weeks. Full elimination typically occurs within 3–4 weeks.

Is septic tank smell outside dangerous?

H₂S at low outdoor concentrations is unpleasant but not dangerous. In confined spaces concentrations can be harmful. Always ventilate before inspecting.

Does the septic tank need to be emptied before treatment?

Not necessarily. If the tank is not full, CleanWaste can be applied directly. Emptying is only needed if the tank is overloaded.

Are CleanWaste bacteria safe for the environment?

Completely. CleanWaste contains only naturally occurring bacterial strains — no GMOs, no chemicals, fully safe for people, animals and the environment.

Can CleanWaste be combined with other products?

Yes, but not with strong disinfectants. These destroy bacterial cultures. Wait 24–48 hours after chemical disinfection before applying CleanWaste.

Laravel

Why does your septic tank smell outside?

Outside septic tank odour is caused by hydrogen sulphide (H₂S) and other putrefaction gases produced when the anaerobic breakdown of organic matter goes wrong. The problem occurs when beneficial bacteria are insufficient — after using chemical cleaners, antibiotics, or extended inactivity. Good news: in approximately 80% of cases the cause is biological and can be completely fixed without a professional.

Biological causes (fixable without a professional)

● Too few beneficial bacteria in the system
● Bacterial die-off from antibacterial cleaning products
● Imbalance following antibiotic use
● Organic overload (e.g. after parties or guests)
● System dormant after long absence

Mechanical causes (require a professional)

● Faulty aeration blower or pump
● Abnormal liquid levels (leak or overflow)
● Blocked drainage pipes
● Damaged membranes or filters
● Tank urgently requiring emptying

CleanWaste: the biological solution

CleanWaste contains billions of beneficial bacteria that, poured down the toilet, reach your septic tank directly. They out-compete the putrefaction bacteria producing H₂S, improve organic breakdown, and eliminate odour at its source within 1–4 weeks.

Practical guide: 4 steps to fix the smell

Identify the cause

Check the mechanics first (blower running, no overflow). If everything is normal, the cause is biological.

Shock treatment

Pour 500 ml of CleanWaste into the toilet once a week for 2 consecutive weeks.

Avoid saboteurs

For 4 weeks, minimise disinfectants, bleach and antibiotics entering the system.

Maintenance dose

After the shock phase, 100–250 ml per month keeps the balance stable.

Starter

Starter Bottle

Ideal for first-time treatment or acute odour shock

1L biological concentrate bottle
Measuring cup
Quick-start guide

€30

1L

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⭐ Most Popular

Family Bottle

3-month biological balance maintenance for families

3L biological concentrate bottle
Measuring cup
Monthly dosing calendar

€70

3L

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Best Value

Annual Bottle

Full-year proactive wastewater system care

5L biological concentrate bottle
Measuring cup
Annual dosing schedule
System health checklist
Priority email support

€100

5L

Order Now →

Septic tank smells outside – what to do?

Why does your septic tank smell outside?

Biological causes (fixable without a professional)

Mechanical causes (require a professional)

CleanWaste: the biological solution

Practical guide: 4 steps to fix the smell

Starter Bottle

Family Bottle

Annual Bottle