Blocked Manhole: What are the Causes & How to Unblock it?

Keith Baker

By Keith Baker

Last Updated on May, 2024

Are you seeing the warning signs of a blocked manhole?

Then you have come to the right place to know what to do next. In this complete guide, we are discussing the reasons for a clogged manhole, warning signs, tools needed, and FAQs.

So keep reading till the end to find out everything you need to know to fix the problem step by step.

Quick Summary

  • Blocked manholes can be caused by various factors, including seasonal changes, heavy rainfall, and the accumulation of debris.
  • Signs of a blocked manhole include slow water drainage, unpleasant odors, and gurgling sounds.
  • To unblock a manhole, one should first locate the manhole, take necessary safety measures, and then use tools like drain rods and a garden hose.

Reasons for a Blocked Manhole

water is blocked through a manhole on the road

Before fixing the blocked drainage hole, you need to find out the reasons for the blockage. Let’s see what the culprit for all the trouble is.

Seasonal Changes

What if those fallen leaves on the road end up in a manhole during autumn?

It’s a common reason for the drainage holes to get blocked. So you have to make sure those leaves are cleaned and disposed of properly.

Otherwise, you’ll have to do the nasty job of unclogging the manholes later.

Heavy Rain

Heavy rain can bring leaves, trash and other debris to the manholes and end up blocking them.

So, you need to keep a close eye on those drains during rainy seasons. That way, you can identify any blockage before it turns into a disaster that erodes your wallet.

Accumulation of Debris

Did you know that a blocked drain can flood the property and streets?

Debris, trash, twigs and leaves can block a manhole and make it overflow. You have to monitor and maintain the drains regularly to prevent this from happening.

It’s always better to nip it in the bud.

Signs of a Blocked Drainage Hole

If you suspect that there’s a blocked sewer opening, these are the signs you have to look out for:

  • Water draining away more slowly than usual
  • An unpleasant smell coming from the drain
  • A gurgling sound coming from the drain when water is running or flushing
  • Wastewater resurfacing from the sink or toilet
  • Raised water levels when flushing

How to Unblock a Blocked Manhole?

unblocking a blocked manhole using a pipe

Imagine that you have all these warning signs coming from a drain. So what’s next?

Unblocking a manhole isn’t a pleasant job to do. You need to be careful for your own safety. Let’s see what steps you should follow to fix the problem.

Locate the Manhole

First things first. You have to identify the manhole before fixing the visible blockage.

In a private property, you’ll find the relevant manhole for your plumbing system in the garden, yard, or driveway. But if a public manhole is blocked, you have to look for it on the street or pavement.

Once you have located the manhole, you have to clear the area to make it easier and safer to deal with the blockage.

Take Safety Measures

How to protect yourself while doing this nasty job?

You need to wear a mask, protective gloves, and footwear to protect yourself from germs, sharp objects, and harmful gases.

It’s easier to follow the safety precautions when cleaning a private manhole. But you need to warn the pedestrians if you are going to deal with a public manhole on a street. It’s better to display warning signs and cones to alert the public.

Clothing and Tools Needed

Here’s what you need to collect before attempting to clean a drainage hole.

Protective Clothing

  • Disposable overalls
  • Face mask
  • Rubber gloves/gauntlets
  • Safety goggles

Tools Needed

  • Buckets
  • Bin bags
  • Garden hose
  • Drain rods
  • Manhole cover keys / large slotted screwdriver

How to Unblock it On Your Own?

Let’s get straight into the business. These are the steps you have to follow if you take a DIY approach towards unblocking a manhole:

  • First of all, you need to take all the safety precautions and put on safety clothing and accessories. The clothing should fit you properly while allowing you to perform the task safely and comfortably.
  • It’s better if you have someone to help you in this step. You have to pull up and remove the manhole cover using its keys or a screwdriver. Make sure to keep the cover aside without letting it fall into the manhole.
  • Now, this is the gut-wrenching step. You have to remove the debris by hand and clear the blockage as much as possible. Make sure to put the debris straight into a bag and dispose of it properly.
  • Then, you have to insert the drain rods into the drain and twist them clockwise with a little pressure. You shouldn’t twist them anti-clockwise, as the joints can get unscrewed.
  • You can put water from a garden hose to check whether the blockage is resolved. The backlogged sewage level will drop, and the water will drain easily if the blockage has been cleared.
  • You can also flush a toilet or run water from a sink to check whether the blockage is gone. If the job is successful, you can clean the gloves, clothing, and tools with water from the garden hose.
  • Make sure to put the manhole cover and double-check whether it’s properly replaced. Otherwise, it will cause an injury to someone.
  • Finally, you can dispose of the waste, clean the area (preferably with a pressure washer), and breathe a sigh of relief!

Related Guide: Can You Cover a Drain Cover in the UK?

How to Use Drain Rods?

Drain rod sets come in handy in unclogging a blocked pipe or drain. They are very flexible rods made of polypropylene. Drain rods are about one metre long. Let’s see how to use them.

  • You can connect two drain rods securely and attach a plunger head at one end.
  • Then, you have to insert the drain rods into the drain and rotate the rods clockwise.
  • You can release any blockage by pushing with the plunger head.
  • When you’re done, make sure to take the drain rods out and clean the plunger head.

When to Seek Professional Help?

Have you tried all the DIY methods, but the problem is still there?

Then the blockage can be too deep for you to reach, or there may be several blockages. So you can contact an expert and seek professional help to resolve the issues.

Professionals can conduct CCTV drain surveys and detect all the problems accurately.

Get Our Drain Unblocking Service Now!!!

How Much Does it Cost to Unblock a Manhole?

a human is unblocking a blocked manhole

Seeking professional help to unblock a manhole can cost you between £80 and £175. A plumber will charge around £50 to £90 per hour.


A blocked manhole can turn into a nightmare when you have to clean it on your own. You can easily identify a blockage when there’s an unpleasant odour and slow water draining.

Leaves, debris, garbage, and household waste are the culprits. You have to put your blood, sweat, and tears to resolve a blockage once it occurs. It’s a tiring process that requires protective clothing and many tools.

That’s why you have to keep a close eye on your drains and manholes to prevent clogging. Vigilance and regular maintenance can save your time and money from going down the drain.


You should check for blocked manholes twice a year, particularly during the rainy seasons and autumn.

Items that cause manhole blockages include debris, leaves, garbage, twigs, toilet paper, and sanitary towels.

Tools used for unblocking a manhole include drain rods, manhole cover keys, buckets, and garden hoses. Protective clothing is also necessary.

To unlock a manhole, you typically use a manhole cover key to lift the cover.

When drains are blocked, water flow is obstructed, leading to backups, overflows, and potential property damage.

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