How many gallons of drinking water per person per day

Photo by Park Street on Unsplash

Water is the most precious resource on the planet. Our current technologies cannot yet produce cheap, clean water to replace natural water found in rivers or lakes or groundwater. As the population grows, demand for water increases while supply continues to shrink. So, we must conserve water; there is no way around it yet. California, which is often hit with long-lasting, multi-year droughts, has come up with a water efficiency standards for its agencies that calls for 55 gallons of water per person per day. The 55 gallons per person per day for indoor residential water use is not intended as an enforceable standard for individuals. It is one of several elements used to calculate the overall efficiency standard for a service area. Thanks to trigger-happy newsmedia and social media, some people are now perplexed and mad about this. This got me to thinking about water usage in my personal life. I wanted to calculate how much water I consume daily. So I used simple google research to come up with the ballpark figures. Let me share my findings here.

How many ways do we use water daily?

First, let’s make sure we are talking about in-house water usage. I am not looking into outdoor water usage such as watering the lawn. So I have identified the following as primary usage of indoor water:

• Water for drinking
• Water for taking a shower
• Water for toilet and bathroom usage
• Water for cleaning dishes
• Water for cooking food

How much water do you need to drink?

It seems like an average adult should be drinking about eight 8-ounce glasses of water each day. This means most people should drink about 2 liters or half a gallon of water each day.

How much water is needed for a typical shower?

The Environmental Protection Agency (EPA) estimates that the standard showerheads use 2.5 gallons of water per minute. The average American shower lasts approx. 8 minutes. So we are talking about 20 gallons of water per shower!

How much water is needed for toilet use?

Depending on the age of the toilet, an average flush can use anywhere from 3.6 gallons to 1.6 gallons. Assuming you have the newer ultra-low-flow (ULF) toilets, which an average flush volume of 1.6 gallons, the daily usage would be approximately 9.1 gallons per person per day.

How much water do you need to wash dishes?

The average dishwasher uses 6 gallons of water per cycle; the average Energy Star-rated dishwasher uses 4 gallons per cycle.

If you don’t use a dishwasher and do it the old fashioned way by hand, you are going to need 27 gallons of water per load.

In fact, an Energy Star certified dishwasher can save almost 5,000 gallons of water per year.

Also, if you rinse the dishes before you stick them in your dishwasher, you are wasting a lot of water. Pre-rinsing wastes more than 6000 gallons of water per household per year! Most newer dishwashers can handle bits of food as long as you scrape the big stuff into the trash first!

How much water do you need for cooking food?

It was hard to find a general answer to this question. People eat a variety of food and therefore, cooking varies from home to home. For example, a person that eats pasta every day will need a certain amount of water vs. someone who eats a steak or chicken or a vegetarian meal. My best guess is that we use anywhere from a quarter gallon to half a gallon for cooking. I am still looking for a better answer to this.

Water Footprints of Common Food Items

While researching the answer for average water usage for cooking, I learned a lot about how much it costs in terms of water usage to produce various food items. This was very shocking to me, and I wanted to share it here.

Globally, agricultural production accounts for 92 percent of our water footprint. In the United States, meat consumption alone accounts for a whopping 30 percent of our water footprint.

• Chicken: 518 gal/lb, Beef: 1847 gal/lb, Pork: 718 gal/lb
• Pasta: 222 gal/lb, Rice: 299 gal/lb, Bread: 193 gal/lb
• Broccoli: 34 gal/lb, Cauliflower, Asparagus: 258 gal/lb
• Tomato: 26 gal./lb, Eggplant: 43 gal/lb
• Cucumbers: 98 gal/lb, Lettuce: 28 gal/lb
• Tea: 108 gallons of water for each gallon of brewed tea
• Coffee: 1056 gallons of water for each gallon of brewed coffee
• Beer: 296 gallons of water to produce one gallon of beer
• Wine: 872 gallons of water to produce one gallon of wine
• Chocolate: 2061 gal/lb, Vanilla: 15159 gal/lb

My Calculations

After adding up the daily usage for drinking, shower, toilet, dishwashing, and cooking, I came up with daily usage of 36.1 gallons per person. This appears very low!

But, the Survey Says…

According to the United States Geological Survey (USGS), on average, a person uses about 80–100 gallons of water per day for indoor home uses! They also point out that the most important use of household waster is to flush the toilet, and the second-largest use comes from taking showers and baths!

Where to Go From Here?

So my calculation seems way off when compared to USGS. I trust their numbers a lot more than mine. No matter which number is right, we need to watch our water usage as water is so precious and likely to become the most sought after resources of the coming decades. Also, we must think of the developing and under-developed nations where water is a life or death decision-maker. We should all think about our water usage and curb as much as possible.

Many local governments now have laws that specify that water faucets, toilets, and showers only allow a certain amount of water flow per minute. Water agencies in some areas, such as here in Atlanta, Georgia, offer rebates if you install a water-efficient toilet.

I also found this interesting info-graphic in “liter” :)

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