How to spot the signs of a collapsed drain
The tricky thing about a collapsed drain is that it does not always give you one clear, obvious sign.
It builds up quietly. You might notice a few small issues, slow flushing, odd smells, or water not draining like it used to, and brush them off. Over time, those little warning signs often point to something bigger happening underground.
At ASL Limited, collapsed drains have been caused by everything from root intrusion and ground movement, to poor installation, vehicle weight, or just time and wear.
Here is how you can spot the early signs and avoid a costly mess later on.
1. Slow drains that do not clear, even after rodding or jetting
If you have already tried clearing a blockage and the problem keeps coming back, that could mean the pipe is damaged or collapsed, restricting the flow. You might clear the water, but the problem returns days or weeks later. A collapsed pipe does not just block, it holds onto debris and catches waste like a ledge. Over time, it clogs up again, no matter how often you clear it.
2. Gurgling noises or air bubbles in toilets and sinks
These sounds usually mean air is getting trapped in the system. It is a sign that water is not flowing smoothly, and may be hitting a break, dip, or obstruction. Think of it like a traffic jam. Water wants to move through, but something is in the way.
3. Bad smells that will not go away
A collapsed or cracked pipe can let foul air escape into places it should not, such as your home, your garden, or around the manhole. It can also stop waste from flowing properly, which means waste sits still and rots, causing nasty odours. Do not ignore those smells, especially if they seem stronger after rain or heavy water use.
4. Soggy patches or sunken ground in the garden
If wastewater is leaking into the soil, you might notice damp areas even in dry weather, grass growing faster or thicker in one spot, or even the ground starting to dip or sink. This is a key sign that your drain has failed underground, and water is escaping into the surrounding soil, washing it away bit by bit. Patios have collapsed, gardens have turned to marsh, and even driveways have sunk from collapsed drains left unchecked.
5. Sewage smells or wastewater coming back up the pipes
This is the one that makes people call fast. If you are getting smelly grey water backing up through the toilet, or seeing sewage coming up through the manhole, something is seriously wrong. More often than not, the cause is either a complete blockage or a collapsed section of pipe stopping all flow.
So what should you do?
Here is what we recommend. A partially collapsed pipe might still drain for now, but it will not last. Jet and suck everything clean with equipment and the tanker. Book a CCTV drain survey — it is the fastest, most accurate way to see what is really going on underground. Get a professional diagnosis, not guesswork, and a clear quote and repair options, whether it is a patch, lining, or excavation.
If you are in Surrey, Hampshire, Berkshire, or West Sussex, ASL Limited can help. Collapsed drains have been fixed under driveways, conservatories, gardens, toilets, kitchens, and more. You will always be shown the footage, everything will be explained clearly, and it will be fixed properly.
Final thought: do not wait until it collapses completely
Once it completely blocks, you could be facing raw sewage leaks, flooded homes, and thousands in repairs. Trust your instincts. If something does not feel right, get it checked.
Need help with slow drains or suspicious smells?
Call ASL Limited on 0800 181 684. Let us take a proper look before things get worse. You will get answers, not guesses.
We cover Surrey, Berkshire, Hampshire, West Sussex and South West London.
