Are there any studies on the water usage of tiny homes? How do manufacturers determine the quantity of water a single house will use?

Bailey,

I did not find any scientific studies on water usage in tiny homes, searching on the internet and in scientific research databases.

I do not know what other builders methods of water usage computation are, I will explain mine though.

1. I make a list of the individuals that will be occupying the home on a regular basis and some notes on their normal behaviors.

2. I factor in some assumptions based on human physiology.

3. I gather the water consumption of all the fixtures I am calculating for.

4. I build a spreadsheet to assist me in my calculations.

Some things that I find are typical with most people I have talked to about water use issues. 

-Most people bathe daily, water consumption can vary greatly. At my home our shower head uses 2.5 GPM (gallons per minute) and while my shower averages 8 minutes (8x2.5= 20 gallons of water used) my spouse takes an average of 17 minutes to shower and come out feeling clean and refreshed (17x2.5= 42.5 gallons) so our monthly water usages are considerably different (600 gallons vs. 1275 gallons)

-Most people use the restroom an average of 6-8 times per day at 2.5 gallons per flush that is 15-20 gallons per day.

-Clothes and dish washers differ wildly in water usage both from model to model and also based on the type of cycle selected.

-Handwashing dishes uses considerably less water than the comparable amount washed in a dishwasher, in my experience.

Our home of 3 uses about 6-10 thousand gallons of water per month where we live, a lot of it to water our garden and for bathing.

I hope this helps.

Sincerely,

Chris Galusha