A Bad Smell From Your Drain: What It Means & What It Will Cost to Fix

What That Bad Drain Smell Usually Means

A persistent bad smell from a sink, shower, or floor drain is rarely just a nuisance. It's a symptom. In most cases, it means there's a problem with the water seal in your plumbing trap, a partial blockage beginning to decompose, or a more serious issue with a sewer vent. The smell itself is often sewer gas – a mixture of decaying organic matter – escaping into your home.

The most common culprit is a dried-out P-trap. This is the U-shaped pipe under your sink or shower designed to hold a small amount of water, creating a seal that blocks gases from coming back up. If a drain isn't used regularly, this water can evaporate, breaking the seal. For floor drains in basements or utility rooms, this is very common.

If the trap has water but the smell remains, you're likely dealing with a partial blockage. Hair, soap, grease, and food waste can build up and start to rot inside the pipes, producing that distinctive rotten egg smell. In more serious cases, a damaged or blocked sewer vent pipe on your roof can cause negative pressure, pulling the water seal from traps and allowing gas into the house.

The Standard Fixes & Our Clear, Upfront Pricing

We believe you should know what you're paying for before we start any job. Here’s a breakdown of the standard investigations and fixes for a smelly drain, and how we price them.

First, we always start with a diagnostic visit. This is a fixed-price visit where our engineer will identify the source of the smell. They'll check all relevant traps, use a drain camera if needed to look for blockages, and inspect accessible venting. This visit gives you a definitive cause and a fixed-price quote for the fix. The price for this initial assessment is always published on our website.

If the issue is simply a dried-out trap, the fix is quick. Our engineer will run water to refill the seal and may apply a safe deodoriser. This is often included in the diagnostic visit if no further work is needed.

For a partial blockage causing decay and smell, a drain clearance is required. We don't charge by the hour for this; we have a fixed price for clearing a blocked sink, shower, or bath drain. This covers the use of our drain rods or high-pressure jetting equipment to remove the build-up completely, restoring free flow and eliminating the smell source. The price varies slightly by location (like a kitchen sink versus a shower) but is always itemised and agreed upon upfront.

If the camera inspection reveals a more complex issue, like a damaged seal or pipe or a problem with the vent stack, we will provide a separate, fixed-price quote for that repair. This could involve replacing a section of pipe or clearing a roof vent. We will never proceed with this additional work without your explicit approval of the quoted price.

Can You Fix It Yourself First?

It's worth trying a few things before calling us. If a drain hasn't been used in a while, simply run water for a few minutes to refill the trap. For sinks and showers, you can try flushing with a mixture of hot water and baking soda followed by vinegar, then more hot water. Avoid harsh chemical cleaners, as they can damage pipes and often don't reach the full blockage.

If the smell returns quickly or persists after these steps, you have a deeper issue. That's when our diagnostic visit provides value. You pay for an expert diagnosis and a clear, fixed-price solution, not for guesswork or open-ended hourly labour. We believe transparent, published pricing gives you the confidence to call when you need to, knowing exactly how our services are structured.