How to unblock an outside drain

Let's start with a little reminder of the types of drains that lead water away from our homes.

Foul water drains carry away domestic wastewater from sanitaryware like showers, toilets and sinks, and appliances like washing machines and dishwashers.

Surface water drains drain away rainwater collected from roofs or balconies through gutters and run-off water collected by drainage channels or French drains which can be found in the hard surfaces surrounding the home.

There can be many reasons why an exterior drain gets blocked.

Excess rainfall

Blockages can occur following heavy rainfall, storms or floods. Rainwater can get mixed with matter like soil, silt or dead leaves. This debris is carried by the water and can start to build up. It's not uncommon to see mud and silt under your drain cover after big storms, and this waste can end up clogging your outside drain.

Work machines

Have you recently had a construction machine pass over your exterior drainage system? Used a digger to dig out a hole for a pool or had a heavy truck come to deliver construction materials to an outbuilding you're in the process of renovating? These types of machines can damage roads so it's easy to imagine the kind of damage they can do to an underground drainage system that is not buried deep enough.

Tree roots

Got a tree growing not far from your drain? It's possible that its roots have made their way into your drain in search of water and are now spreading through the system.

Septic tanks

Is your septic tank full? Septic tanks can reach maximum capacity meaning they are unable to collect any more wastewater to the point where they can overflow.

Now that we've taken you through a few of the most likely reasons why an outside drain might get blocked, let's look at how to identify the issue at hand and find a solution to unblock your drain.

Start by opening your manhole and drain covers. Exterior drainage systems comprise different points of access. PVC drains feature drain covers that can be easily unscrewed or popped off in order to access your drain.

You'll also find manhole covers or drainage channels at the end of these drainage systems. Open them up and inspect to identify where the issue is located. If you have a full septic tank that is no longer performing as expected, you'll have to get in touch a specialist company to visit with a vacuum truck to empty your tank.

The same goes for any blockage found to be outside of the boundaries of your property. If the issue is in the sewer system it is your water company's responsibility to deal with the problem. In this case, contact your local water company. However, if you've carried out your checks and found the issue is on your end, it's time to think about how to unblock your drain.

Steps

1. Inspect the water under your drain covers

2. Dislodge the blockage using the right tool

Required skills

No particular skills are required.

Time required

2 to 4 hours

Number of people required

1 or 2 people

Tools and equipment

• Drain snake

• Garden hose

• Drain jetting nozzle

• Pressure washer

Safety and workwear

• Protective gloves

• Protective clothing

• Mask

Please note: this is a non-exhaustive list; be sure to match your personal protective equipment to the job at hand.

Use a trowel to remove any solid matter that has found its way into your drain such as silt, dead leaves or stones.

Then use a bucket, a bottle with the top cut off or any other container to remove any remaining water down to drainage level.

Use a drain snake

Insert a drain snake into the blocked drain making sure it is long enough. A drain snake, or plumber's auger, is a long metal auger with a hooked end which is used to pierce through the blockage. On the other end, there is a handle which is used to advance the drain snake along the pipe turning the hook as it goes.

Insert the hook end into the blocked drain and push it along by cranking the handle.

You can then move the drain snake back along in the other direction. The aim is to move as much built-up material in the drain as possible.

Use a drain snake that is longer than the pipe itself and repeat the process until the auger reaches the full length of the drain. If the auger gets stuck and can't reach the end of the system, you can use the length of the drain snake inside the drain to identify exactly where the blockage is whether this be a piece of broken pipe or a tree root. In this case, you will have to dig down to where the drain snake gets stuck so you can inspect the pipe and carry out repairs.

Use a garden hose and drain jetting nozzle

This method is similar to the one described above but means you won't have to buy a drain snake.

Insert a garden hose into your drain until you reach the blockage and then turn on the water.

Move the hose back and forth to try and dislodge the blockage as you would with a drain snake. This method doesn't often work but it's worth a try before investing in a drain snake.

If your drain is still clogged, use a drain jetting nozzle. These nozzles are designed to be fitted onto garden hoses and concentrate a jet of water towards a certain point. The pressurised water should work to break down the blockage and clear your drain.

You can choose from a number of different nozzles. Some are designed to fit onto garden hoses while others can be fitted to a pressure washer lance for optimum efficiency.

This is the method most commonly used by drain jetting companies and will manage to break down the vast majority of blockages.