We love saving money. Everyone loves saving money. But many people neglect the simple adjustments which can save a lot of money over time. We’ll look at one today – the low flow showerhead.
As you might know, we bought the Niagara 1.25 GPM showerhead a week ago and documented it in our annual budget report. We’ve been impressed by the quality for such a low price. Water pressure is excellent and it’s tough to notice the decrease in water volume.
According to the math below, you’ll recoup the purchase price in less than one month.
To begin, I’ll have to estimate your water usage. I’ll try to stay conservative on the numbers but it’s tough to please everyone. In addition, I’ll use the 2.5 Gallon Per Minute (GPM) showerhead to calculate totals. It seems like the 2.5 GPM heads are widely used and older models have even higher usage.
I’ll assume you take 25 showers over the course of a 30-day period and that your average shower lasts 8 minutes. Here we go:
Traditional 2.5 GPM showerhead:
25 showers at 8 minutes each means that you will shower 200 minutes each month. Multiplying 200 minutes by the 2.5 gallons-per-minute flow rate, you will use about 500 gallons of water each month.
Niagara Low-flow 1.25 GPM showerhead:
Continuing the math. Multiplying 200 minutes by the 1.25 gallons-per-minute flow rate, you will use about 250 gallons of water each month. You’ve just cut usage in half.
Now lets look at the yearly totals.
- With a traditional, 2.5 GPM showerhead, you’ll use 6,000 gallons of water per year.
- With a 1.25 GPM, low-flow showerhead, you’ll use 3,000 gallons of water per year.
So for us as a couple, we’ll save 6,000 gallons per year (3,000 x 2). Adjusting for inflation and basing my cost on this 2004 article, I’ll estimate water at $2.25 per 1,000 gallons.
We will save $13.50 this year in water alone.
Calculating the cost to heat the water requires a little more work so I’ll draw from a trust source – the Ask Mr. Electricity site:
“Energy required to heat a tank of water
- A Btu, or British thermal unit, is the amount of energy needed to raise one pound of water from 60°F to 61°F at sea level.(Wikipedia)
- A gallon of water weighs 8.33 lbs.
- If the incoming water is 60°F and we want to raise it to 123°F, that’s a 63°F rise.
- Heating a gallon of water thus requires 8.33 x 63 = 525 Btu’s, at 100% efficiency.
Cost to heat water in a gas tank
- A typical gas tank water heater is only 59% efficient. So it takes 525 ÷ 59% = 890 Btu’s to heat a gallon of water in a gas tank.
- One therm is 100,000 btu’s. So one Btu is 0.00001 therms.(Pacific NW Natl. Lab.)
- 890 Btu’s is 0.0089 therms.
- So we’ve got 0.0089 therms to heat a gallon of water, or 0.0089 x 40 = 0.356 therms to heat a 40-gallon tank.
- At $1.42/therm, it costs 0.356 x $1.42 = $0.51 to heat a 40-gallon tank.
- Another source comes up with a similar figure: 0.40 therms for the tank (based on 0.11 therms to heat 11 gallons of water. (Multi-housing Laundry Association)
- MHLA also says it takes 3.3 therms to keep 11 gallons hot for one month.
Cost to heat water in an electric tank
- A typical electric water heater is 90.4 to 95% efficient. Let’s call that 92.7% on average.
- So it takes 525 ÷ 92.7% = 566 Btu’s to heat a gallon of water in an electric tank.
- One kWh is 3413 Btu’s, so one Btu is 0.000293 kWh.
- 566 Btu’s x 0.000293 kWh/Btu = 0.166 kWh.
- So we’ve got 0.166 kWh to heat a gallon of water, or 0.166 x 40 = 6.63 kWh to heat a 40-gallon tank.
- At $0.11/kWh, it costs 6.63 x $0.11 = $0.73 to heat a 40-gallon tank.”
For a close middle point, we’ll use an estimate of 1.5 cents/gallon for heating costs. This will vary depending if you have an electric or gas water heater, it’s efficiency rating, and the local cost of gas/electricity.
So 6,000 gallons of water multiplied by 1.5 cents/gallon means we’ll save roughly $90 per year in heating costs.
That’s over $100 per year from a single shower and 2 individuals!
Yes, these are rough estimates. Yes, they are too simplistic for most real world applications. But I think they prove my case.
Let me know if the numbers make sense to you. Have you made the switch yet?