A Beginner's Guide to Water Leak Detection

by ‐ Tags: water efficiency, tracking and benchmarking

We’ve talked about catching water leaks before, but mainly the ones that are easy to find – spikes.  There’s another type that most people don’t really talk or think about that are much more difficult to catch.  But armed with a little bit of knowledge about typical water use in residential buildings, you’ll be hunting down this type of leak in no time.

Spikes vs Continuous Leaks

With a spike you’ll see a drastic increase in your water usage, which is a sure sign that either your utility company billed you incorrectly or that all is not well in your building.  You can read more about that in our previous blog post on the topic.

A continuous water leak is less obvious and takes a little more work to detect.  Sometimes it’s been going on for years or since the building was built.  If you’ve been monitoring your water usage, then you likely just consider this the baseline usage for your building.  However, when you start to really get into the numbers that’s when a leak like this will reveal itself.

Just How Much Water Should My Building Be Using?

That is an excellent question and it's essential to understanding if you might have a continuous leak. We like the multi-family specific numbers provided by Building Well, shown below.

Water Usage Benchmarks  
High Performing Building < 60 gal/bedroom/day
Average Building 60 - 120 gal/bedroom/day
Poorly Performing Building 120 - 200+ gal/bedroom/day


To figure out where your building falls, find a recent water bill, determine your water use in gallons (some may be in CF, CCF, HCF, thousand gallons, or another measurement), and see how many days were covered by the bill.  Divide the number of gallons by the number of days and then divide that number by the number of bedrooms in the building.  Then see how you compare to the table.

Once you know how you stack up, consider if there are unique aspects to your building that may be leading to higher than normal usage that is actually normal for your building, such as irrigation, a swimming pool, or water-intensive commercial space on the same water meter.

As a quick example, I’ll use my water bill.  The relevant section looks less than helpful, but it does contain all the info I need - the usage and the dates the bill covers.  Unfortunately, nowhere on the bill does it say what units the usage is measured in.  After some searching on the town’s web site I was able to determine that it’s CCF, which I converted into gallons.

Water Usage on Bill

The next step was to determine the number of days this covered.  My quick and easy way to get that number is to put both dates into a spreadsheet and then subtract them.

Excel Tip

Now I know that I used 8,229 gallons in 87 days in a building with 2 bedrooms, giving me an average daily usage of 47 gallons/bedroom, which is right around average for a single family home in my area, according to the WegoWise database.

Case Study

One WegoWise user has water data back through mid-2008 which gives them a good historical perspective on what is “normal” for their building.  They had fairly steady water usage, though it was high at an average of 160 gallons/bedroom/day.  In the fall of 2012 there was a modest spike and they subsequently began doing water retrofits, which spanned over 3 months.  Once those retrofits had been completed, their water usage had decreased significantly below historic usage levels.  Since then they’ve average consumption of 109 gallons/bedroom/day, which is saving them over $2000 per month.  160 gallons/bedroom/day had seemed normal to them, but it could be better categorized as a steady state of water waste.

 Pre-retrofit Data

Baseline data (prior to retrofits)

Complete water history

All data - note the significant drop at the end of 2012