How to unblock standing water from a garden drain

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There are many types of different garden drain and all of them have the potential to block.

Gardens and other outside spaces naturally accumulate organic debris, dust and dirt from the surrounding environment. These materials over time can build up in grates and pipes leading to standing water blockages.

Roof gutters and grated channel drains can easily become clogged with leaves and moss. These can discharge into drainage pipes and soakaways, however, the most common scenario is a pea trap or surface, sump, drain becomes clogged.

​These small and normally square, grated, drains are easily prone to silting and blockages. In this article we will show you how to unblock a garden drain with standing water step by step. 

Why is my garden drain blocked?

Many typical garden drains have a U-bend built in. This allows for a continuous water seal between the pipework and the outside.

This prevents odour from escaping from the drain and allows wastewater to pass through easily. The problem is, over time, these U-bends can become filled with silt and debris.

This can lead to a complete blockage and continuous standing water. 
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Particularly in much older homes it is common to find square grated sump drains installed to low points within surfaces.

Many of these have no U-bend and simply have a vertical pipe which feeds into the ground below.

​These are these easiest drains to block as they rely on the natural permeability of the ground to drain. In both cases you will need to unblock your drain for them to continue to draining water away.  

How to unblock a garden drain step by step

​Regardless of if you have a sump drain, U-bend or pea trap you will need to investigate by hand. Put on an elbow length rubber glove before you begin:

Step 1:

Remove the grate which is installed over the garden drain. This can normally be achieved using a screwdriver or long chisel.
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Step 2:

Slowly lower your hand down into the drain feeling for obstructions. Be careful, there may be sharp material fragments which have fallen into the drain! 
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Step 3:

Feel around gently to discover where the pipe leads and what the blockage is. Usually you will find many years worth of fine silt and muck. You may also find a large obstruction like piece of wire or wood. 

Step 4:

Remove any obstructions you find and scoop out any silt or muck you find and dispose of it.
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Step 5:

​Take care not to force your hand too far down the pipe and risk getting stuck! Make sure you can manoeuvre your hand around well as you work. 

Step 6:

When the drain is clear of obstructions water will drain away easily. You then need to flush out the drain with a hosepipe. When the water backwash is clean and draining freely you have successfully unblocked the drain. 
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Step 7:

It is a good idea treat your drain with some disinfectant, this will stop germs from breeding and relieve any odours. 
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What can I buy to unblock a garden drain? 

Sink plungers

​Sink plungers are traditionally used to unblock sinks. However large plungers can be used to unblock small garden drains. The large, rubber sucker creates suction within the drain which can dislodge blockages. 
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Sink plunger on Amazon

Plumbing snakes

​Plumbing snakes are ridged but flexible wire rods with a spiked or hooked end. These can be fed, down, along pipes and used to break through and disperse blockages. 
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​Drain auger on Amazon

Drain rod sets

​Drain rods are generally for much larger drains and sewage pipes. These interconnected, flexible pipes have a ridged but flexible circular disc at the end. This can be fed far down a blocked pipe and smash through backed up blockages. 
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​Drainage rods on Amazon

Drain unblocking solutions

​There are many drain unblocking fluids and gels on the market today. Most of these contain strong acids which slowly break down blockage material such as hair and other materials. 
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​Drain un-blocker gel on Amazon

'Thank you for reading our article on how to unblock a garden drain. Below we have included some other garden drainage articles you may find useful. 

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