Installation rehausse pour fosse septique

How to install a Polylok riser

Project overview

Difficulty: intermediate

Total time: two hours

A riser is a vertical shaft that extends from your septic tank’s access port to the surface of your lawn. The top of the shaft has a lid, which is easy to spot and safe for septic professionals to access at any time.

Risers are a must-have for many septic systems. They eliminate the need to dig into your yard and search for your septic tank lids when it’s time to inspect or pump your system.

This solution comes in two parts: the riser itself and the adapter ring that connects it to your septic tank. The riser and adapter ring must be compatible sizes and must be paired with a lid that matches the riser’s diameter.

Polylok offers risers and adapter rings in a variety of access port diameters:

Polylok risers are easy to install, lightweight, and simple to blend into your backyard.

What size of riser should I get?

Measure the diameter of your septic tank’s opening and note it down. The size of the riser and adapter ring you get should match the size of your septic tank’s opening.

What type of riser lid should I get?

The size of the lid should match the size of the riser you have chosen. While a standard lid will do the trick, Polylok also has a heavy-duty lid for 24’’ risers if you want something more durable.

In some areas, regulations require that you install an additional safety lid. Contact a local septic expert to know if you need to get one.

We highly recommend installing a riser safety lid as a precaution.

Which Polylok adapter ring should I get?

You should get the Polylok adapter ring that corresponds to the shape of your septic tank’s opening.

The Polylok square adapter ring is perfect for older septic tanks models with square openings. For newer models of septic tanks with rounded openings, you should use the Polylok round adapter ring.

How many risers and adapters do I need?

Septic tanks usually have two openings. Make sure you have enough parts and hardware to install a riser, a lid, and an adapter (if needed) over each opening.

Polylok designs its risers so they can be stacked on top of one another. The lid should be slightly above soil level to prevent any runoff water from leaking into your septic tank.

You can stack as many risers as you want, so long as you conform with local regulations. Check these rules carefully because the excess weight of too many risers could damage your septic system. If you have any doubts, refer to Polylok’s instructions or call a local septic expert.

What you need for this project

  • Polylok adapter ring kit, which includes:
    • 8 anchor bolts
    • 8 nuts
    • 8 washers
    • closed-cell foam gasket
    • 1/4” drill bit
  • Polylok adapter ring
  • compatible Polylok riser(s)
  • compatible Polylok lid
  • drill
  • hammer
  • circular saw (if there are anchor rings)
  • shovel (if the lids are buried)
  • utility brush
  • 3/16’’ wrench
  • stainless steel screws (provided with Polylok risers) 


  1. Make sure you have everything you need before getting started.
  2. Find the location of your septic tank. If you don’t know where your tank is located, check out these tips for finding buried septic tank lids.
  3. Clear the area over the lid. If it’s buried, dig a 32” diameter hole that reaches your septic tank lid.
  4. Remove the lid. Do not enter the system.
  5. Clean the area around the outer rim.
  6. Cut the anchor rings (if any).
  7. Centre the adapter ring over the access port. If you are installing a riser-to-riser adapter ring, skip to step 10.
  8. Use the outer holes on the adapter ring as a template to identify the location of each anchor hole. The Polylok square adapter ring has eight anchor holes. The corrugated pipe adapter ring has four.
  9. Use the 1/4" masonry bit to drill a 1'' to 1-1/2'' deep hole through the adapter ring at each anchor hole.
  10. Turn over the adapter ring. Heat the bottom before installing the gasket.
  11. Install the gasket.
  12. Ensure the two ends meet to create a watertight seal.
  13. Pull the plastic backing off the gasket. If you are installing a riser-to-riser adapter ring, centre it over the access port, install it evenly and securely, and skip to step 20.
  14. Centre the adapter ring over the opening.
  15. Drill into the concrete at each anchor hole. Insert an anchor bolt into each hole.
  16. Lightly tap each anchor bolt with a hammer.
  17. Place a washer and nut on each anchor bolt.
  18. Tighten each nut with a 3/16’’ wrench.
  19. Cut off any excess piece of anchor bolt.
  20. You can add riser extensions as needed:
    • Install the watertight seal.
    • Place the extension over the seal and secure it with the provided stainless steel screws.
  21. Snap the lid on top and secure it with the provided stainless steel screws.
  22. Repeat the previous installation steps for your second lid.

Video disclaimer

This installation video was filmed with generic, non-Polylok risers. Every step demonstrated can be referred to as instructions to install Polylok risers.