A septic tank riser generally refers to a specific type of extension that is added to a septic tank. This structure can make accessing the tank easier, and help in the removal of any tank lids. It may also make locating a septic tank easier. Many building regulation codes now require that a riser is part of the septic unit.

A septic tank riser is usually specially manufactured, because it has to fit the precise dimensions of a tank. Risers generally range from six inches (15.25 cm) to 12 inches (30.48 cm) in height, and have a diameter of 12 (30.48 cm) to 24 inches (60.96 cm). Many of these risers are also made so that they can be stacked one on top of another. This is ideal if a septic tank is buried deep underground.

The purpose of a riser is to raise the height of the septic tank lid. Lids are locked onto the top of a septic tank, and are held down by stainless steel screws. Some risers may also include structural ribs. This can be helpful in areas where winter is harsh, as the ribs prevent the build up of frost, which can destroy the riser.

Some of the common materials for septic tank risers include PVC, concrete, and polyethylene. Concrete risers can be very heavy, making them difficult to install. This often means that heavy lifting equipment is needed for installation. These risers may also be more prone to damage and leakage. A concrete riser may also not be very aesthetically pleasing.

A polyethylene septic tank riser is typically resistant to corrosion that may be caused by chemicals or soil. Gaskets seal this type of septic tank riser, making the unit more secure. This type of riser usually prevents foreign materials from getting into the tank, and can reduce the chance that dangerous gases, such as methane, will leak from it.

A PVC septic tank riser weighs less due to its lightweight construction material. This type can be much easier to install and require less effort from workers. PVC risers are sealed much like the polyethylene models. This also prevents any leakage or entry of materials into the septic tank.

Septic tank risers can vary in cost. Concrete risers are usually the cheapest. Since PVC and polyethylene models have more advantages, they can be more expensive. Companies that professionally install septic tanks may also install septic tank risers.