Question
We have a willow (not weeping) that grew very close to our septic field. It seems to be shooting out more little trees from it's roots. We cut them down and they come back.  How can we get rid of them?  I'm afraid they'll damage the septic.

Answer
These are sprouts from the root system. The sprouts will not harm the septic lines but the roots from the willow may well get into the lines and clog the lines. The best way to keep the sprouts down is by just mowing them as they come up. IF the roots from the tree are above ground a little you can cover the roots with sand but only add a couple inches over the roots.

A weeping willow grows to a spread of about 35 feet and their massive root system can be expected to spread AT LEAST that far. Because sewer lines provide the perfect growing conditions for these aggressive, water-seeking roots (loads of nutrients and moisture in an environment with a fairly constant temperature), they should never be planted anywhere near a septic system or drain field. All it takes is a hairline crack in your pipe, and the trees' tiny root tendrils will head toward this favorable environment.
This tree species grows fast and its roots are experts at seeking out water. The nutrient-rich water from leaky sewer pipes or cracked water lines acts like a magnet to the roots of these water-loving trees.

Tree roots do not cause drains or sewer pipes to break, but they will invade and clog drains that have pre-existing cracks and resultant leakage.
Drains are usually six to eight feet below ground level, while tree roots grow almost exclusively in the upper two feet of soil, because they not only need nutrients, but also oxygen to survive. When drains leak, they provide oxygen and nutrient rich water deep in the soil, which allow tree roots to grow deep into the soil and get into the already cracked drain pipe.

Sewer pipes especially the older clay or felt type can be invaded by the roots of many trees. This may clog the sewer pipes and cause back up and will need to be rooted out. Newer PVC type sewer pipes will not be effected.

Tree roots are often blamed for blocking sewer pipes; however, tree roots only penetrate sewer pipes that were previously damaged by other factors such as poor construction, aging and soil settlement.

When the small exploratory roots come into contact with cracked or leaking pipe, they are stimulated to grow vigorously often into the damaged pipe.

The combination of roots and solid wastes will usually develop into a partial or complete blockage of the sewer line.

The following is a list of treatments available to homeowners to correct blockage problems in the sewer line.
Plumbing contractors have equipment for removing blockages from the sewer lines. This method provides short-term solution.
Chemical root inhibitors are available to kill roots.
Copper sulphate can be used to kill roots within sewer lines.
Sewer pipe liners are inserted into the sewer and positioned into the damaged area of the pipe.
Replacement of the sewer pipe in severe cases is the only effective solution.  


Underground sewer pipes are subject to attack by tree roots. The small roots work their way through the pipe connections and, if given sufficient time, they will effectively clog the system.

Copper sulphate, poured down the fixture drains, will kill the roots but not necessarily remove them completely. A plumber's snake can be used to clear the roots out of the pipe, but this requires considerable effort, especially when the roots are large and densely packed in the pipe.

Plumbers use a powered rotor with a flexible shaft inserted into the pipe, and this will clear the pipe effectively. These are temporary measures, however, for the roots will come back into the pipe. Special sewer pipes are available, which are so constructed that roots cannot penetrate the pipe joints. When a sewer line is repeatedly attacked by tree roots, the only lasting remedy is to dig it up and have this type of pipe installed.