Why Your Outdoor Drains Smell in Summer (And How to Fix It)

If there’s a foul smell coming from your patio drain, driveway gully, or rear waste pipe — you’re not alone.
Summer is prime time for drain smells, and here in Exeter, we get dozens of callouts when the heat kicks in.

Here’s why it happens — and what you can do before it turns into a blockage (or a BBQ ruiner).

What Causes Outdoor Drain Smells?

A few likely culprits:

• Grease and food waste congealed in warm pipes

• Decomposing organic matter (leaves, soil, paper)

• Dry traps letting sewer gases up

• Partially blocked gullies that aren’t draining fully

• Old or cracked pipework leaking foul odours

In the summer heat, all of these smells get stronger and rise faster, especially when the system hasn’t been flushed recently.

How to Fix It (DIY First Steps)

Before calling a drainage engineer, try this:

• Pour a kettle or two of hot water down the drain

• Add baking soda + white vinegar — let it fizz, then flush with water

• Check for visible debris in surface drains and remove by hand

• Flush external gullies using a hosepipe (if safe to do so)

Avoid using harsh chemical drain cleaners — they often damage pipework and don’t solve deeper blockages.

Still Smelling? Time for Jetting or Inspection

If smells persist, it could be a sign of:

• A partial blockage further down the system

• A collapsed pipe or misaligned gully

• Sewer gases coming up through a dry or damaged trap

In these cases, we usually recommend:

• CCTV drain survey (to confirm the issue)

• Drain jetting (to remove deep-set waste)

• Gully or pipe repairs (if needed)

Final Tip from EPM

You don’t have to live with a stinking patio drain all summer.
Most of the time, it’s a simple clean and flush — and we’ll let you know if it’s anything more.

EPM now offers professional drain jetting and inspections in Exeter and surrounding areas. No mess, no nonsense.