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Choosing the Right Size Well Seal for your Well

By Aidan Hennebry

Measuring your well casing in order to choose the properly sized well seal can feel like a daunting task if you’ve never done it. Thankfully, it’s actually a really simple process with just a bit of experience, and that’s what we’re happy to provide you with today.

About Well Seals

WS50 (top)Well seals are measured according to the seal on the inside diameter of the casing. This is what we’ll be measuring to ensure you get the right size seal for your well.

Well seals are designed to create a compression seal against the inside wall of the casing, so it’s important that you don’t have an incorrectly sized seal, or your well will not be safe from possible contaminants.

How do I measure a Well Seal?

Using a ruler or tape measure, we can easily determine the size of well seal you will need for your particular well.

Step 1:

You want to ensure that the zero on your ruler or tape measure is on the edge of the casing’s inside wall. In our experience, using a ruler can be easier than a tape measure because the hook on the end of a tape measure can make it difficult to get the zero right on the edge.

Tip: If you’re struggling to measure with the instrument you have, align the 1” mark to the inside of the well casing instead, and just subtract 1” from your final measurement.

Step 2:

The goal is to measure across the very centre of the well casing to the opposite side. The easiest way to know that you’ve done this is to pivot your ruler from the zero point until you get the largest possible measurement. This ensures that you are perpendicular to the ruler or tape measure on the other side of the casing. Again, double check that your ruler or tape measure hasn’t drifted off of the zero mark.

Step 3:

To the nearest 1/16th of an inch, write down the measurement that your ruler or tape measurePicture1 indicates. This corresponds with the proper well seal size that you need to cover it. Use the chart on the right to help with this process:

An Item of Note:

Depending on the type of well seal you choose to cover your well, such as ABS Plastic (WSP Series), Cast Iron (WS Series), or Steel Plate (WSS Series), you may find that not all sizes are available.

For example, an 8” x 4” well seal is only available as WSS8040 (Steel Plate). This seal eliminates the need for an WSS8240 as it has a range that covers 8” to 8-1/4” casing inside diameters.

Well Seal VS Well Cap

It’s important not to mix up a well seal and a well cap. A well cap seals on the outside of the well casing,WTC-A06-1 whereas a well seal seals on the inside of the casing.

Which one you need largely depends on where you live and what is common in your area (and, of course, what code your local jurisdiction regulates). If you are unsure of what to use, the simplest approach is to replace your cap or seal or with the same that was on there before. If you still have questions or concerns, feel free to contact us directly and we can help you decide.

In Summary

As you can see, the process for measuring a Well Seal is rather simple in principle, and can be a little tricky in application depending on a variety of factors. We hope you learned something today!

Be sure to check out our other articles on BoshartU related to all things water well.

Have further questions about this subject?


Head over to Boshart's Knowledge Base: technical product information, guidelines, and more. 

Tags: Well Seals