Our septic tank riser kits are measured by their inner diameter and height. The first number in their names is their inner diameter in inches, and the second number is their height in inches. This means that a 20’’x 11’’ riser kit has an inner diameter of 20 inches and a height of 11 inches.
The bottom ring of the riser kit is what attaches the assembly to the septic tank. There must be enough area around the access port to properly attach the ring to the septic tank. For example, a 20’’x 11’’ kit has an adapter ring that has an inner diameter of 20 inches and an outer diameter or 26 inches. That means the maximum distance across the access port must be 20 inches or less, and the top of the septic tank must be large enough to allow a ring with a 26-inch outer diameter to seal to it.
If the adapter ring is secure, it is okay for the riser system is a little larger than the hole.
*Above is a picture drawing of the dimensions of the base for the kits*
*ALSO--- Please be fully aware that this particular height riser kit, comes with a 3" riser/safety pan that has an inner diameter of 17" due to a slight bevel*
*There is an upcharge to upgrade from a domed lid to a flat lid*
*Dome Lid option will add an extra 1" of height to the kit*
*Concrete lids are to be removed prior to the installation of your new riser kit*
Please ensure that you are ordering the correct diameter and height riser kit before placing your order. If the incorrect size is ordered, return shipping is the customers responsibility.
1 - 20" Heavy Duty Tuf Tite Septic Tank Flat Or Domed Lid