What risers do and why you might need them

Risers are extensions that bring your septic tank's access ports closer to ground level, so you do not have to dig down three or four feet every time you need to pump or inspect the tank. A riser is a PVC or concrete pipe that sits on top of the existing access hole, raising the lid to within a few inches of the surface. If your tank lid is buried deep, installing risers makes maintenance easier and safer—and it prevents you from accidentally driving over the access point.

Most septic tanks are installed with the lid 18 to 48 inches below ground. Over time, soil settles and grass grows over the spot, making it hard to locate. A riser solves this by creating a permanent, visible marker and eliminating the digging step. Many homeowners install risers when they have the tank pumped, since the access hole is already open.

Key Takeaways

  • Risers are PVC or concrete pipes that extend your septic tank's access port to near ground level, eliminating the need to dig before pumping.
  • You will need to know your tank's dimensions, the diameter of the existing access hole, and whether your tank is concrete or fiberglass before ordering a riser.
  • Installation requires removing the existing lid, setting the riser on top of the opening, sealing it with concrete or adhesive, and installing a new lid on top of the riser.
  • A professional septic contractor can install risers in one to two hours, and the cost typically ranges based on your location and tank type.
  • Once installed, risers require no ongoing maintenance beyond keeping the lid accessible and checking it during routine tank pumping.

Measuring your tank and choosing the right riser

Before you order a riser, you need to know three things: the diameter of your access hole, the depth of the hole below ground, and the material of your tank. Most residential septic tanks have access holes that are 18 to 24 inches in diameter. Measure across the opening at ground level. If you are unsure, ask your septic pumper the next time the tank is serviced—they see the opening every time they work.

Risers come in standard sizes: 12 inches, 18 inches, 24 inches, and 36 inches in diameter. They also come in different heights, typically 6 to 12 inches tall, though you can stack multiple risers if you need to raise the lid higher. The height you choose depends on how deep your current lid sits. Measure from the top of the existing lid to where you want the new lid to sit—usually 4 to 6 inches above finished ground level.

Risers are made of PVC (plastic) or concrete. PVC risers are lighter, easier to cut if you need a custom height, and less likely to crack. Concrete risers are heavier, more durable in freeze-thaw climates, and blend in better if appearance matters to you. For most homeowners, PVC is the practical choice. You can order risers from septic supply companies, plumbing suppliers, or online retailers that stock septic equipment.

Preparing the tank and removing the old lid

Have your tank pumped before you install a riser. A full or nearly full tank makes the job messier and more dangerous—you risk exposure to gases and sewage. Schedule the pumping and riser installation on the same day if possible, since the access hole will already be open and the pumper can help you locate it precisely.

Once the tank is empty, use a pry bar to carefully lift the existing lid. It may be stuck from years of settling soil or rust. Work slowly and do not force it—a cracked lid is harder to replace than a stuck one. If the lid is bolted down, unbolt it first. Set the old lid aside in a safe place; you may need it later if you decide to remove the riser.

Clean the rim of the access hole with a brush or cloth to remove dirt, algae, and debris. The riser needs to sit flush against the tank opening, so any buildup will create gaps that let soil or water in. If the rim is cracked or uneven, you may need to have a contractor assess whether the tank itself is damaged before proceeding.

Setting and sealing the riser

Lower the riser carefully into the access hole so it sits centered and level. It should rest on the rim of the tank opening, not inside the hole. If the riser is too large to fit, you have ordered the wrong size—do not force it. If it is too small, it will not seal properly and soil will wash in around the edges.

Once the riser is positioned, seal the gap between the riser and the tank rim. Most installers use a flexible polyurethane sealant or septic-safe concrete. explore the sealant around the entire perimeter where the riser meets the tank. Do not use regular caulk or silicone—these break down in the septic environment. If you are using concrete, mix it to a thick consistency and trowel it around the base, feathering it slightly so water runs away from the riser.

Let the sealant or concrete cure for the time recommended on the package—usually 24 hours—before installing the new lid. This prevents the riser from shifting while the seal hardens.

Installing the new lid and finishing

Once the sealant has cured, set a new lid on top of the riser. Septic tank lids come in plastic or concrete. Plastic lids are lighter and easier to remove for future pumping. Concrete lids are heavier and more permanent-looking. Make sure the lid fits the riser diameter—a 24-inch riser needs a 24-inch lid. The lid should sit flat and not rock.

If you want the riser to be less visible, you can install a hinged or locking lid cover that sits flush with the ground. These are optional but useful if you have children or pets, or if you want to protect the access point from debris. Some homeowners paint the lid or cover it with a decorative grate.

Mark the location of the riser on a map or diagram of your property, and keep a record of it with your septic maintenance records. This helps future owners and service technicians find the tank quickly. Take a photo of the installed riser from above and from ground level for your records.

When to call a professional

If your tank lid is more than 4 feet below ground, if the access hole is an unusual size, or if you are unsure about the tank's condition, hire a septic contractor to install the riser. They have the tools to measure accurately, the experience to seal properly, and the ability to spot problems—like a cracked tank or settling soil—that you might miss.

A contractor can usually install a riser in one to two hours. The cost depends on your location, the riser material, and whether additional work is needed, but most jobs fall in a moderate price range. If you are having the tank pumped anyway, ask the pumping company whether they offer riser installation; many do, and bundling the services may save money.

Do not attempt to install a riser if the tank is full, if you see cracks in the tank or rim, or if the ground around the tank is unstable or waterlogged. These are signs that the tank itself may need repair before you add a riser.

Maintaining risers after installation

Risers require almost no maintenance. Keep the lid accessible so the pumper can remove it easily. Do not park vehicles over the riser or use it as a stepping stone. If you notice the lid sinking or the riser shifting, contact a contractor—this usually means the seal has failed or the ground underneath has settled unevenly.

Every few years, inspect the seal around the base of the riser. If you see cracks or gaps, explore fresh sealant to prevent soil and water from entering. This is a straightforward task you can do yourself with a caulking gun and septic-safe sealant.

Frequently Asked Questions

Can I install a riser myself if I have never done plumbing work?

Yes, if the tank is empty, the access hole is a standard size, and you are comfortable measuring and explore sealant. The main risk is sealing it incorrectly, which lets soil wash into the tank. If you are unsure, a contractor is worth the cost. The job itself is straightforward, but the seal is critical.

What if my tank has two access holes?

You can install risers on both, or on just the main one. Most homeowners riser only the primary access port. If the second port is for a distribution box or pump chamber, ask your pumper which one is used most often and riser that one first.

Do risers work on fiberglass tanks?

Yes, but fiberglass rims are more fragile than concrete. Use a flexible sealant rather than concrete, and avoid heavy pressure when setting the riser. A contractor familiar with fiberglass tanks is the safer choice.

Can I remove a riser later if I change my mind?

Yes, but it is more work than installing one. The sealant will have hardened, and you may need to break it loose with a pry bar. Once removed, you will need to seal the access hole again with concrete or a fitted cover. Most people leave risers in place once installed.

What if the riser is not level after I install it?

An unlevel riser can cause water to pool on one side of the lid. Remove it, clean the rim, and reset it, checking with a level as you go. If the tank rim itself is uneven, you may need a contractor to assess whether the tank has shifted or settled unevenly.