Blocked Drain Causes: Tree Roots, Concrete & Broken Pipes

24 May 2018    Blocked Drains

Main sewer pipes can get blocked in other ways than toilet & wastewater pipes (see Blocked Drain Causes: Fat, Toilet Paper or Objects), for example, tree roots growing into the pipe joints and soil blocking the pipe when it is broken by vehicle traffic.

Tree Roots Growing in the Pipe

People often think that tree roots could not be the cause of their blocked drain because there are no large trees in their property. Unfortunately tree roots can travel very large distances, so it is possible for the roots from your neighbour’s tree to penetrate your pipes.

Particularly in times of low rainfall or drought tree roots will seek out the nearest source of water and food, which can often be your sewer or storm water pipes. Any small crack or break in a pipe, or even badly glued joints can be an entry point for a tree roots to access your pipes and thrive on the constant water and food source.

An electric eel can be used to pull tree roots out and clear the blockage. But the method of using an electric eel doesn’t usually remove all the tree roots, but merely ‘punches’ a hole through the roots, leaving the surrounding roots behind. A water jetter or jet rodder is a much better tool for removing tree roots, as the high pressure water can cut out all of the roots and flush them down the pipe. If all the tree roots are removed, the roots are less likely to grow back in a short period of time.

Cracked or Broken Pipes

It doesn’t matter if it is a small or large break in your sewer pipe, both can allow fine tree roots to enter the pipe and grow quickly. Once tree roots gain access to the constant food source of sewer and water they can grow very quickly and completely engulf the inside of your pipe creating a blockage.

A large break in a drain pipe can allow dirt from around the pipe to fall in and either block the pipe or create a sink hole as the dirt is constantly washed down the pipe. A sink hole (where the ground collapses) that is close to a house and its footings can cause significant damage to the structural integrity of the building. It can also create further damage such as cracked walls, severed pipes and in severe situations part of the house can fall into the hole.

Crushed / Collapsed Pipe

If pipes are laid too close to the surface or not surrounded with sufficient gravel or sand, they can easily break when heavy machinery such as a car, truck or excavator travel over the ground. If the pipe is partially or fully crushed then small obstacles or excessive toilet paper can easily get caught and cause the pipe to back up and cause a blockage.

Concrete Inside a Pipe

Strangely enough a common question is “Can you remove concrete from inside a pipe?” It is not uncommon for people to move into a newly built or renovated house and very quickly get a blocked drain.

This is because a common practice of tilers is to pour the leftover grout from their job down the floor waste rather than dispose of it appropriately. The grout / concrete then settles at the bottom of the pipe and sets hard leaving the pipe partially blocked. The affected area of pipe is often located below the concrete slab of the house and the blocked area of pipe not able to be dug up easily.

Depending on the severity of the blockage either a suitable jet rodder or a robotic cutter will need to be used to remove the concrete within the pipe.