The Sneaky Cost of Long Showers
Long, relaxing showers are a pleasure that many of us enjoy. The warm spray feels good on our skin and soothing on achy muscles. The pitter patter sound of the water falling drowns out the sounds of the rest of the world and we feel protected from the disturbances of our busy lives - like we're in a safe little cocoon of guaranteed privacy and relaxation. These benefits do not come without costs, however, and you may be surprised at just how much long showers are costing you. Perhaps we haven't given it much thought, or perhaps we didn't know how to figure out how much of our bills were because of showers. In this article, we're going to take the mystery out of how much showering actually costs.
The Cost of Water:
The most obvious cost of showering is the price of water itself. If you have a well, electricity to pump the water and maintenance on the pump and well replace a water bill from the city. Less obvious are sewage costs, which may be separate but also are added right into water bills in many communities. If you have a septic system, I probably don't have to tell you the problems that overloading it causes. We looked at the combined cost of water and sewage in our community, which we have every reason to believe is a normal, suburban city in the Midwest. The combined cost of water and sewage is $.015 per gallon and does not include monthly administrative fees or the 13% price hike for exceeding 15000 gallons per billing cycle. With the standard shower head flow rate of 2.5 gallons per minute, a 45 minute shower uses 112.5 gallons of water at a cost of $1.68 per shower. Compare that to a ten minute shower that uses just 25 gallons of water for a cost of $0.375 and see the savings of $1.30 per shower. $1.30 isn't a lot? Well, in one year that's $474 extra dollars per person taking the longer showers and we're not quite done yet.
The Cost of Heating Water:
Water doesn't come warm enough to shower in, so we have to heat it. Calculating the cost of heating water is trickier since we must understand a little about energy requirements and account for heater efficiency, but don't worry - we'll walk through it step by step in a moment. For those who don't care to stick around through the mind-numbing number-crunching, I'll give you a spoiler and tell you that a 45 minute shower uses 28 cents of natural gas per shower, bringing the cost of each shower to $1.96. A ten minute shower uses just 6 cents of natural gas for a total shower cost of $.435. The total cost for a 45 minute shower for a year is $715.40, compared to just $158.77 for ten minute showers. This means that two house members taking 45 minute showers each cost $1113 more that two people each taking ten minutes showers. Uhhh... Airfare to Hawaii, anyone? On to the boring math part.
Here's the Boring Math Part:
Cost of Gas = Cost/BTU * PoundsOfWater * Temperature Increase / Efficiency
The first thing to know is that natural gas is sold per Mcf, which equals 1000 cubic feet. Each Mcf contains approximately 1,037,000 BTU (British Thermal Units) of energy. The cost per Mcf when these calculations were done was $3.69, but note that prices have risen dramatically and at the time of this writing are up to $5.52. Still using the lower number, the cost per BTU works out to $.00000356277 per BTU. It may seem insignificant but stay with me.
Water weighs 8.33 pounds per gallon and at 2.5 gallons per minute, a 45 minute shower uses 112.5*8.33=937 pounds and a 10 minute shower 25*8.33=208.25 pounds. This is important because it takes one BTU to increase the temperature of water by one degree F.
To determine how many BTU are needed to heat each gallon of water, we need to decide the starting and final temperature. Since the water temperature varies by location and from season to season, we'll use 55 degrees F as an average starting point. The temperature of the shower is a matter of personal choice, but we'll use an accepted standard shower temperature of 105 degrees, meaning we need to raise the temperature of our water by 50 degrees.
Efficiency: This efficiency refers to the water heater. A standard gas water heater is about 60% efficient. This means that for every 100 cubic feet of natural gas you buy it, only 60 are used to heat water and 40 are wasted out the chimney!
If we revisit our formula above, heating the water for a 45 minute shower costs:
Cost of Gas = Cost/BTU * PoundsOfWater * Temperature Increase / Efficiency Cost of Gas = .00000356277 * 937 * 50 / .6 Cost of Gas = .28 per 45 minute shower, or $102 per year
Cost of Gas = Cost/BTU * PoundsOfWater * Temperature Increase / Efficiency Cost of Gas = .00000356277 * 208.25 * 50 / .6 Cost of Gas = .06 per 10 minute shower, or $22 per year
By adding the cost of gas per shower to the cost of water per shower, we can see the total cost
45 min cost = $1.68 + $.28 45 min cost = $1.96 $1.96 * 365 = $715.4
10 min cost = $.375 + $.06 10 min cost = $.435 $.435 * 365 = 158.77
I'm going to be honest - I'm really impressed if you've read this far, but I felt it was important to show where our numbers came from and how to calculate your own annual cost of showering.
And on the topic of costs, I'm afraid to say that financial expenses aren't the only costs that come with longer-than-necessary showers. There are very real negative effects on health, the environment, and family harmony that we will tackle in later articles. For now, just understanding that the expense can be far more than we realized may be enough to convince us that it's time to reduce our shower usage. Whether through self-discipline, new household rules, or a green product like The Happy Dad Valve that automatically limits how long a shower-user has hot water, you stand to save a significant amount of money every year by taking action.