Happy Drains Blog

What Causes A Blocked Manhole?

Manholes. What are they? You seem them every day. Well if you leave your home you will do. There are thousands of them situated around London and the rest of the country. We did try and do some digging to find out exactly how many manholes the UK has but we couldn’t find a single estimated figure, if you know the answer please get in touch as it will help us sleep easier at night.


What are they?

Simple, a small opening in a paved or road area that leads right to the sewers, this can be a bit of a drop, that’s why you will see it covered with a frame or manhole cover. They are traditionally around 4-5ft in width, but beyond the cover itself, the lid is comprised of adjusting rings that all play a vital role as it’s in-line with the pavement grade. This ensures overflowing wastewater is collected safely and kept securely to the sewage lines.

Here’s a fun fact for you, manholes have been in place since the early 19th century, and as you can imagine, have been developed to a much higher standard over the decades. Traditionally back in the day, they were built from the ground up, but today it’s from the ground down.



We touched upon this earlier, but there are more than just the main running manholes that you see in roads and pathways, you will also have one situated at your property or shared building.

If you’ve never spotted it, you’ve clearly never had a blockage. If it’s a lovely Autumn morning, pop outside and have a wander around and see if you can locate it. The likelihood is that at this time of year fallen leaves will be covering it up!


Fallen leaves and heavy rain are the main causes of blockages for manholes. The rain drifts everything in its way and blocks up the manhole causing flooding, if then left untreated this can cause endless trouble so we advise taking action immediately if you spot a visible blockage.

Pop on some protective gloves, safety lift the manhole cover if possible and begin removing any visible debris, taking care throughout the removal process. 

If you do this and you still are seeing flooding, then it’s time to call one of our industry professional experts to come and take a look at it for you.

We’re here for you 24 hours a day and you can contact us on 0800 849 8099 or email the team at service@happydrains.co.uk