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How Much Water Do I REALLY Use Inside My Home?

How Much Water do I REALLY use inside my Home?


“My home uses a lot of water and I need the 1 ½” water main (or whatever size you have – 3/4″ to 1 ½”) that delivers the water into my home. Bigger is better and required when it comes to water main size into my homeMy family will suffer, my plants will die, and my fish will dehydrate if I were ever to downsize that water main or install any piece of water treatment equipment smaller than the line size that would be installed on said main.”

Let’s see if we can bust that myth with some simple math eh?



What dictates that GPM flow rate across the main into the home?

  • Size of home?
  • # of bathrooms?
  • # of people?
  • # of fixtures?


None of those factors on their own.  So what does then?  Simple: The # of fixtures opened at the same time and the GPM each allows to flow through it dictates the GPM through the water main.


What’s IAPMO?? (International Association of Plumbing and Mechanical Officials)

The study titled, “Peak Water Demand Study Probability Estimates for Efficient Fixtures in Single and Multi-family Residential Buildings” was published in January of 2017.

The study reviews Hunter’s Method (1940) and Wistort’s Method (1994) for the calculation of peak water demand in a home or building.  If you REALLY like math, I suggest digging into it. However, in summary for our purposes…62 cities in 9 States participated in the national water use survey.  Results from 1,038 homes were analyzed with 2,821 occupants in the homes.

Surprisingly the per capita water usage was only about 60 gallons per day.

Unfortunately there was still 16% of the water usage attributed to leaks!

Aside from the leaks though there are 6 common fixtures in most homes.  Here is the breakdown of daily usage according to the study:


Watch a great video summarizing all these key points (approximately 14:45 in length):

The Key Takeaway is that water usage inside a home is relatively low and typically averages between 1 and 4 gallons per minute.

If you want to calculate the usage in YOUR home, download a copy of the spreadsheet you saw me use in the video HERE. (if download does not automatically begin, right click and choose “save as…”)


Our goal when specifying units is “right-sizing.”  This means that we can, will, and do suggest units that are smaller than the water main line size every day.  With less than a 1% return rate, our case summaries support our size suggestions.


Would you like to find out how Fluid Dynamics can protect your home or business?  Click HERE to schedule a free consultation.

Comment below and we will be sure to respond to them all!