How spreadsheets lock drainage designers into formulaic cells

6 min read

Spreadsheets can be a powerful tool used by civil engineers and hydraulic modelers to run drainage calculations. Software like Microsoft Excel can help model complex drainage systems and deliver outputs that some engineers are comfortable with for given plans and projects, but they are a blunt tool for in-depth drainage design.

Why engineers stick with spreadsheets

In our conversations with new customers, we always want to hear about the tools they’re transitioning from so we can ensure that our software will tackle all their pain points. We also ask about spreadsheets when we have conversations with designers and modelers at water conventions.

Here are a few reasons engineers tell us why they rely on spreadsheets:

These objections should not be completely dismissed. Which tool you choose to use is every drainage designer’s prerogative. In point of fact, spreadsheets are very good at some things. They’re a good complement to drainage design, particularly when it comes to transporting data into and out of your models. If you need to get your data into or out of a specific format or move it from one design app to another in the normal chain of development on a project, spreadsheets can be a huge time saver.

Why we think they shouldn’t

But all three of these objections are easily knocked down by better technology that’s purpose-built for drainage design.


Drainage design software is based on standard drainage design formulas and can output results to a higher degree of accuracy than spreadsheet-based calculations. It can also fit your designs to specific national or custom-built rainfall and runoff standards. The software also updates responsively, decreasing the possibilities for user error and making iterative design easier.


Our own InfoDrainage is built with Autodesk design language and integrates with existing civil design software like Civil 3D, but perhaps more importantly, it provides a visual interface and outputs that can be understood not just by the people on your direct team but by all stakeholders on a given project. With a proper app, you designs can be updated quickly based on everyone’s feedback, which is easy to show to others. This is a comfortable place to be.


We can’t speak for every drainage design app, but InfoDrainage is trusted by the world’s leading drainage designers, is built on generally accepted drainage calculations, and has decades of development and support behind it.

The history of Microdrainage and its next-gen successor, InfoDrainage.

Reasons to limit the use of spreadsheets in your design work

Engineers are adept at understanding areas of improvement, spotting inefficiencies, and making changes to their workflows or designs to address them. As one engineer to another, here are some additional reasons that I think spreadsheet designers should reconsider their approach.


Despite the general assumption that spreadsheets are more trustworthy than software, MarketWatch found that 88% of spreadsheets contain at least one error, and the list of spreadsheet horror stories continues to grow from industry to industry. It would be naive to assume engineering operations were immune, although the risks associated with spreadsheets are often ignored (eg, increased cybersecurity risks).

In short: engineers should not rely on their own attention to detail and error-spotting abilities when it comes to their professional reputation.


Spreadsheets can be chaotic, hiding formulas, and presenting data with conventions that are not intuitive (eg, AM198 or G92 cell references). This extra layer of representation between you and your models makes it harder to make necessary adjustments and increases the opportunity for errors.


Spreadsheets decrease efficiency for drainage design workflows and result in less efficient drainage designs. The workflows that spreadsheets necessitate are inherently slow and tedious, and they also don’t naturally optimize, meaning that your drainage designs are only as efficient as your inputs.

Lack of visualization

Spreadsheets are incapable of visually presenting data, making client buy-in more difficult for drainage designs and impeding executives’ understanding of a given project.

The uncalculated costs of spreadsheets

Cost is probably the biggest unspoken reason engineers still use spreadsheets, and it’s very understandable considering how under-resourced water companies can be, particularly publicly funded utilities. Excel is ubiquitous. Your organization already has plenty of copies, but if you recorded the time spent creating, customizing, and maintaining spreadsheets and performed a cost-benefit analysis, would spreadsheets really be as cost effective as you assume?

We are most definitely biased, but for a solution that less accurately represents physics and water chemistry, relying on spreadsheets might not be such a great deal after all. They take hundreds of hours to create and maintain. They require you to track down and validate the correct versions of disparate Excel files. Didn’t use the right file? That could result in litigation. Once a spreadsheet becomes sufficiently large and complex, the person who created it must usually explain how it works to anyone who wants to adopt it, making spreadsheets less useful collaboratively, and making both onboarding new staff and losing existing staff more costly. All of these details end up costing more time.

Beyond these downsides, which I will grant you are arguable, I think it’s important for drainage designers to be future-forward. While you don’t have to embrace every new technology like machine learning and AI, as a professional designer you should always be watching industry trends, whether those come about by innovation or due to regulations.

While powerful at calculation, spreadsheets are only as capable as their users and require extensive input, validation, and customization to fit a given projects’ drainage design needs. They result in cookie-cutter designs that have become outdated as drainage designers have shifted away from prismatic flow path design and are paying more and more attention to the natural landscape and environment.

Today’s designers prefer non-prismatic flow paths, and that is not feasible with a spreadsheet. Nevertheless, some engineers would still rather use spreadsheets and default prismatic flow designs because they already understand how that works and don’t want to learn the ins and outs of new software. They may simply modify existing prismatic designs by changing basic dimensions. But this hesitancy to adopt drainage software no longer holds water, particularly as drainage designers turn to more natural-based SuDS-style solutions that seek to design drainage to fit specific projects, rather than the other way around.

While we are clearly biased, when you strip that away and we speak engineer to engineer, I’d implore you to question using spreadsheets for drainage design. Ask yourself, is this really the most accurate, least-error prone, efficient way we could be doing this? Don’t settle for good enough; that’s not why we became engineers in the first place.

Don’t toss out all of your spreadsheets

But don’t throw away all of your spreadsheets. They will always have their place. While they are not a lingua franca for design, they can be a good transport container for data. They are also one of most common ways to output a regulatory report, a way of showing your homework in a standardized format if the teacher asks.

If you’ve been using spreadsheets extensively to facilitate drainage design, download a 30-day free trial of InfoDrainage (no credit card required) and investigate the option of using one comprehensive solution that doesn’t require you to build additional custom spreadsheets to perform dynamic flow analysis, clash detection, 1D/2D analysis, and Deluge analysis.

We think that when you make the switch from a general tool like spreadsheets to a purpose-built tool for the work you do, you won’t want to go back.

Further reading

Spreadsheets are excellent at storing and transporting data, but they aren’t a database or a collaborative tool or very good at automating tasks. When you use spreadsheets in your civil engineering work, follow a few of these best practices and avoid unneccesary risks:

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