Tackling tree roots—a persistent menace to domestic sewer pipes

Press, 11 September 1986, Page 11

Tackling tree roots —a persistent menace to domestic sewer pipes

Trees are an important part of any household scene. They provide shade, shelter from the wind, and enhance the built environment, but there is a sinister, hidden side to many trees which should not be disregarded.

Tree roots can be a persistent menace to domestic sewer pipes. Any tree planted close to your sewer pipes is likely to cause problems. The roots of pohutukawa, willows and poplars are particularly troublesome. It is a problem you do not want but cannot afford to ignore. The Plumbing Information Bureau advises householders to be careful, therefore, in choosing the type of trees to plant and where to plant them.

In their search for lifesustaining moisture and nutrients, tree roots are relentless. Sewer pipes are a source of both moisture and nutrients, and roots “sense” this.

They have been found by-passing stormwater drains in preference to sewer pipes which provide ideal growing conditions.

Roots can travel great distances and some are surprisingly aggressive in their highly sensitive foraging for moisture and nutrients. Roots will take advantage of any and every opportunity to get inside pipes. Usually, roots enter a pipe through faulty joints, but damage to pipes by digging implements, or even the weight of soil, may provide an easy entry. They can invade minute cracks when the growth is new and finer than a strand of hair.

Once inside the pipe, trouble is inevitable. Tiny hair roots are, likely to grow into a fibrous mass spreading long distances through the pipe. Almost certainly the flow through the sewer will be reduced and ultimately a complete blockage will result. Roots that stay in the pipe long enough to become thick and woody may cause so

much damage that the pipes have to be replaced.

Root-invaded pipes and drains will bring you inconvenience and financial loss. Householders are responsible for the drains on their property and in some areas for the drains from their boundary to the public sewer.

Licensed plumbers or drainlayers must be employed to clear roots from blocked drains. The work could cost anything from $5O for a straightforward clearance to hundreds even thousands of dollars if the work requires excavating below expensive paving and possibly replacement of pipes and restoration.

Clearance simply by rodding or using a special cutter is a short-term solution only as the roots will grow back. Removal of the tree or digging up the pipe to seal where the roots entered is necessary.

Some chemical treatments have been developed which kill the tree roots in the pipe but do

not damage the tree. Their effectiveness varies and redosing is required periodically. Obviously, it is far wiser to avoid such root invasion than to face a disruptive and costly remedy after the damage has been done. There are certain trees which you should not plant close to your own or

your neighbour’s household sewer lines, or the public sewer outside your boundary. If you do not know the location of your sewer line, visit your local authority office which has plans showing the location of sewer pipes to individual properties. Copies are available for a small fee.