Toilet Still the Largest Water-Using Device in a Home

Toilet Still the Largest Water-Using Device in a Home
The toilet is regarded as a ready receptacle for all kinds of other items that should not be put down the drain so our industry needs to continually educate homeowners.

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Following a previous article on homeowner water usage, we received an email from a reader challenging the toilet as the largest water-using device in a home. 


“I just read your comments regarding homeowner education and water usage. I do not believe that today’s toilets use the 25 to 40 percent of the daily flow that you indicated. These percentages originated years ago when toilets used 5 gallons per flush. Most modern ones use 1.6 gallons per flush.

If a family uses 300 gpd then the formula is:

300 x .25 = 75 gallons. 75/1.6 = 46.875 flushes per day. That’s 11.75 flushes/day, each, for a family of four.

The same family at 40 percent:

300 x .40 = 120 gallons. 120/1.6 = 75 flushes per day. This makes 18.75 flushes, each, for the same family.”


I agree that it doesn’t make sense that the toilet remains one of the larger water-using devices. In an inspection class I teach we always discuss homeowner water usage and why even in some of the more recent surveys on water use the toilet still comes out on top. 

I look forward to the day the numbers actually drop because it will mean we are doing a better job as an industry to educate homeowners. 

Here are a few reasons why we have not necessarily seen the reduction we might expect: 

  1. One flush is often not enough to clean out the bowl of a 1.6-gallon flush toilet. If it takes two flushes to remove the contents then the reader’s numbers are reduced by one half. When low-flow toilets were introduced, they did not operate as well as those already on the market. So depending on personal use, 1.6-gallon toilets get flushed more than once, which increases water usage. 
  2. Percentages can be deceiving in studies. All other water-using devices in the home are becoming more efficient, including dishwashers, washing machines and showers. They don’t use the amount of water they used to so if all water-using devices have increased efficiency the percentages stay roughly the same. What we should probably concern ourselves with more is the actual amount of water used. 
  3. Unfortunately, the toilet is regarded as a ready receptacle for all kinds of other items that should not be put down the drain. That’s why we tell homeowners not to put anything down the toilet unless they’ve eaten it first. There are way too many products on the market today that actually encourage flushing like cleaning products and wipes. Then there are still all the old standbys including cigarette butts, condoms and feminine hygiene products. 

I’m sure this will not be the last discussion on this topic. The real message is that the homeowner has the final say in terms of how much water is used and industry professionals have a lot of work to do to get homeowners to change their habits. 

About the Author

Jim Anderson is connected with the University of Minnesota onsite wastewater treatment education program, is an emeritus professor in the university’s Department of Soil Water and Climate, and education coordinator for the National Association of Wastewater Technicians.

Send him questions about septic system maintenance and operation by email to

Do you agree with the reader on the toilet’s decreased water usage? Why or why not? Post a comment below.


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