Water Filter vs Bottled Water Cost Calculation: How Much Could You Save?

Are you considering buying a water filter system to reduce costs? And to stop wasting so many water bottles?

We hunted down all the latest 2021 prices for tap water, bottled water, and water filters. Below is our cost comparison which we hope encourages you to ditch the bottle. 

Let’s find out EXACTLY how much you could save. 

1. How Much Can You Save With A Water Filter vs Bottled Water?
2. Quality: Bottled Water vs Filtered 
3. Other Reasons to Stop Drinking Bottled Water
4. Methodology
5. Start Saving

How Much Can You Save With A Water Filter vs Bottled Water?

We’ve calculated these costs on a per person basis*, for an average adult. If you’d like to calculate savings for your family you can multiply the results by the correct number of people.

Water filter pitchers are the most accessible type of water filtration system available. So we’ve calculated water costs based on one of these. Our calculations are based on Brita filters, but an alkaline pitcher could be even cheaper.

Bottled Water vs Pitcher-Filtered Water Costs

Water filter Pitcher Upfront cost: $15 – $35

That’s right. A water filter could save you up to 92% compared to buying bottled water. 

What are our calculations based on?

• An average adult drinks 2.56 liters of water per day
• A liter of filtered tap water costs $0.0296
• A liter of bottled water costs $0.41

Quality: Bottled Water vs Filtered 

What’s really in your bottled water? 

Well, a lot of the time it’s just tap water. One report suggests that over 50% of all the big water brands bottle water from municipal tap water sources. 

Unless you can find ‘spring water’ on the label of your bottle, it probably came from the tap. 

The same report by the Food And Water Watch also found that bottled water is often no safer than tap water. As the municipal water industry is subject to more rigorous safety checks than bottled water, tap water is often much safer.

Bottled water may be purified using a reverse osmosis system, distilled, acid neutralized (alkaline water), or filtered in various other ways. The truth is, most of these methods can be done at home with a much lower price tag.

Other Reasons to Stop Drinking Bottled Water 

Cost is the main focus of this article. However, there are many other reasons you should get your water directly from the kitchen faucet.

Environmental Impact

In the United States, it’s estimated that between seventy and seventy-five percent of plastic water bottles are never recycled. 

Bottles are often “down-cycled” in China. They’re turned into fabric and rugs, rather than recycled into new bottles. This means that the cycle of using crude oil to manufacture more plastic bottles continues. 

Health Concerns

A recent study by the State University of New York in Fredonia found that more than 90% of bottled water samples contained microplastics. While there is no evidence to suggest that microplastic fibers have an impact on human health, this could be concerning for many people.

Methodology

If you’re wondering how we worked this out, we’ve listed all our workings and assumptions below. 

Daily Drinking Water Requirements 

*The adequate fluid intake for men and women is 3.7 liters and 2.7 liters respectively. (U.S. National Academies of Sciences, Engineering, and Medicine)

Around 20% of our fluid intake comes from food (Nutrition Reviews 2011). So the remaining 80% is how much we need to get from drinking water. 

Average daily adequate fluid intake:
(3.7l + 2.7l) / 2 = 3.2L

Fluid required from drinking:
3.2L * 0.8 = 2.56L

For this study, a single person’s daily drinking requirement will be 2.56 liters.

Cost of Bottled Water

We based our calculations on the most popular bottled water brand in the United States in 2020, Aquafina (Statista).

We’ve assumed that anyone drinking bottled water as their main source would look to buy in large case sizes for cost savings. So we chose the largest case we could find for our study. 

At the time of writing (June 2021) a 32-count case of Aquafina 16.9 fl oz bottles costs $6.58 at Walmart.

Volume of Water Per Case 

32 bottles * 16.9 fl oz = 540.8 fluid ounces per case

540.8 fluid ounces = 4.225 gallons OR 16 liters per case

Cost per gallon

$6.58 / 4.255 = $1.56 per gallon

Cost per liter 

$6.58 / 16 = $0.41 / liter

Cost of Tap Water

In 2019, the average residential monthly water bill for an American family of four using 100 gallons of water per person per day was $72.93. (Statistia) 

Monthly total water usage per average family of four (gallons)

100*4 = 400 gallons per day

An average day month has 30.43 days (Wikipedia) 

400 gallons * 30.43 days = 12,172 gallons used per month

Monthly total water usage per average family of four (liters)

100 gallons = 378.541 liters 

378.541litres * 4 = 1514.164 liters per day

An average day month has 30.43 days (Wikipedia) 

1514.164 liters * 30.43 = 46,076 liters 

Cost per gallon 

$72.93 / 12,172 gallons = $0.006/gallon (rounded to three decimal places)

Cost per liter 

$72.93 / 46,076 liters = $0.0016/liter (rounded to three decimal places)

Cost of Water Filters

At the time of writing a pack of six Brita water filters costs $24.99. Each Brita water filter is good for 40 gallons or 151.46 liters (Target). 

Cost of one water filter

$24.99 / 6 = $4.16 

Cost per gallon of filtered water

$4.16 / 40 = $0.104125/gallon

Cost per liter of filtered water

$4.165 / 151.46 = $0.028/per litre

Total cost of filtered water and tap water

Finally, we calculated the total cost of filtered water. 

$0.0016 + $0.028 = $0.0296 / litre 

Get Yourself A Filter and Start Saving 

Filtration systems like Brita water pitchers are a great place to start. You won’t need to do any difficult or expensive installations. Just fill it up and pour. 

And there’s no need for any research either. Head over to our best water filter pitchers article, where we’ve done all the hard work for you.