How to Maintain a Weir

weir box

A weir is one of the best solutions for flow rate measurement thanks to its impressive ability to be precise. If you want to keep that precision high, however, you’ll need to maintain the weir over time. This can be a lot of work, but it’s fairly easy once you know what to do. Learn how to maintain a weir, and discover the steps you won’t want to miss out on.

Maintaining the Weir Pool

Upstream of the weir box, you’ll have to install a weir pool for the device to function properly. The weir pool must be meticulously maintained to ensure that you’re getting the right measurements unaltered by poor approach conditions. The details of cleaning the weir pool are quite simple and straightforward.


Because weirs create a damming effect, solids and sediment tend to build up in the weir pool. Proper maintenance involves clearing out the debris whether it’s weeds, sediment, trash or anything else that may stake a claim there. Additionally, you’ll want to trim the vegetation around the weir pool to prevent any growth or debris from falling in unnecessarily. Keep in mind that trees overhanging the upstream area may need to be trimmed as well.

Maintaining the Weir

The weir itself requires a bit of maintenance if you want to maintain accurate measurements. One of the first steps of the maintenance process should be checking for leaks. If your weir has any leaks, you may find that some of the flow is bypassing or undercutting it. If this gets bad enough, you may be dealing with what is ultimately a failed installation. This is also why you’ll need to fully seal the clean-out doors.


Proper installation of a weir means making it plumb and level. Any variances from that standard will throw off your measurements. Part of general maintenance is checking for any irregularities in that regard. Frost heave is a common cause of shifts that throw off the weir’s positioning. If you find that the weir has moved out of position, you’ll need to modify it to bring it back to standard.

Maintaining the Weir Crest

The crest of the weir is one of the most important pieces of the device, with its positioning and shape being essential for accurate measurements. To keep the weir crest clean, you’ll have to remove any debris or growths along the edge. Anything that can change its dimensions must be removed. If you have flows with high levels of solids, you’ll be doing this quite frequently.


To get the most out of your weir crest, you’ll need to examine the crest for any damage. Nicks or abrasions will have to be repaired. Additionally, you’ll want to make sure that the edge doesn’t get too rounded. While it shouldn’t be as sharp as a knife, it needs enough of an edge to properly aerate the flow passing over it.

Weirs From Tracom

Now that you know how to maintain a weir, you’re ready to take care of one of your own. At Tracom, we offer a variety of weirs along with the option to work with our team to design a custom device. Contact us today to get started!