How tree roots get into pipes
Trees are a beautiful addition to any home although they can become a costly plumbing nightmare if their roots gain access to underground pipes. Tree roots seek out moisture and nutrients to survive, so naturally gravitate towards pipes. If there is a crack, loose joint or basically any access point smaller roots will find their way in, and grow quickly in a short period of time. Clay pipes seem to be the most susceptible to tree root invasion as they are older and are installed in smaller sections than PVC pipe (around 900mm long) with rubber joint seals. This means they have more points for tree roots to enter.
Clay vs. PVC pipes
Clay pipes are joined with rubber rings, unlike PVC which are fused with glue. Rubber has a life span of around 20 years, so they will deteriorate over time. As clay pipes have been in the ground longer, they are also prone to ground movement over time. This may cause cracks or damage to them, allowing tree roots to get in.
Even though 100mm PVC pipes are stronger than most clay pipes they are not exempt from tree root invasion. A leaky joint or a crack may occur when a joint is not installed or glued correctly, or a rubber cap has not been screwed on properly. Generally speaking, PVC pipes should be a lot sturdier than clay pipes as the lengths are longer. Because PVC pipes are laid in 6m straight lengths, there are fewer joints. 100mm PVC pipes used for sewerage are quite significantly stronger than 90mm PVC pipes, commonly used in stormwater.
Once tree roots have made their way into the pipe work, the problem simply worsens over time, as the roots continue to grow becoming thicker, stronger and more entangled. Eventually, it will lead to a blockage as waste becomes lodged on the tree root mass or the mass completely fills the diameter of the pipe.
Solutions to tree root problems
There are a couple of different options when dealing with tree roots:
Some people have asked if chopping down trees will solve pipe problems. The simple answer is no, because chopping trees down will not stop their roots from entering the pipework. The roots often continue to grow and aside from this, the damage to the pipes has already been done. Fig tree roots can travel up to 100m and we have even seen other tree roots travel 6m to 8m under the slab even when they are positioned an additional 4m from the house!
The other problem with killing or removing a suspected tree is that you cannot tell which trees roots are causing the damage unless you chop the roots out and get them tested to see what sort of roots they are. You could dig up your yard tracing tree roots from the pipe back to the tree but again – this is much more trouble than it is worth.