How to Replace a Septic Tank Lid

A septic tank lid exposed outside of a home.
What You'll Need
Metal detector
Measuring tape
Replacement lid

The lid to your septic tank might seem insignificant, but it's actually one of the most important parts in the system. A weak seal around the opening will cause odors to seep out, and it can also allow foreign objects into the tank which can cause clogs in the system. So, it's important that you replace this lid on a regular basis.

Step 1 - Find the Septic Tank

Search and find the septic tank in order to remove and replace the lid. This can sometimes be more difficult than it sounds, especially if you have a larger property. First, try the easy way by either contacting local tank pumpers, past homeowners, or the health department in your area. They may be able to tell you the position of your septic tank and save you a lot of time and effort looking for it.

If the easy way doesn't work, you'll have to find the sewer exit from your house. In an unfinished basement, this will be simple as you can see where all the sewer pipes come together and leave through one of the walls.

If your basement is finished, go on the roof and find the vent that allows sewer gases to escape. The sewer pipe exit will usually come out of the basement wall below this vent. Then, look outside 10 to 20 feet from the location of the pipe exit where there's a square of grass that looks greener and healthier than the rest. Use a metal detector to find the exact position of the tank before you begin digging.

Digging is not necessary if the septic tank lid is above ground as is often the case. Simply go to the patch of greener grass and cut back longer grass or remove debris to access the lid.

Step 2 - Determine the Type of Replacement Lid Required

Most lids are either 21 inches wide or 24 inches wide, so use a measuring tape to determine which you will need. Then, find out what type of material the current lid is made out of. It will either be PVC, high-density polyethylene, or concrete. If the lid is concrete, you may want to consider replacing it with a PVC or polyethylene version since these types are more waterproof and lightweight.

Buy the replacement lid of your choice in the correct size from a large hardware store or a store specializing in septic tank supplies. Expect to pay around 100 dollars for a concrete lid, 225 for a PVC, or 200 for a polyethylene one.

Step 3 - Remove and Replace the Lid

If your current septic tank lid is concrete, you'll need to hire someone with a backhoe to lift and remove the lid and risers since it'll be too heavy to do so yourself. Hire the operator to install the new lid as well if you prefer to stay with the same material.

PVC or polyethylene lids can be removed by yourself or with an assistant according to manufacturer's instructions. The easiest type of septic tank lid to install yourself is a PVC one since bonds adhere easily to the lid making it easier to fasten it to a tank. It's also strong and doesn't need to be treated to make it last. A polyethylene lid will need to be domed to make it stronger. To do this follow the manufacturer's instructions included with your product.

After you're finished, use a shovel to bury the lid again only if necessary.