Water Conservation. The Classic Question of Bath or Shower.

Water conservation is a hot topic these days.  And the amount of water we use in our homes makes up a significant amount of our daily water usage.  Whether you're using water to cook, clean, wash clothes, or bathe, water usage can be significant.  One of the places where we use the most water in the house is the bathroom.  And obviously, we use a lot of water to bathe.  The classic question is:  Do we use more water taking a shower, or bath?

I am going to make the assumption that most people at least know what a bath is and what a shower is.  If not, then we need to have a blog post about hygiene.  It's obvious that a shower and a bath differ in how you bathe.

A shower consists of a constant flow of water, and a bath is a set volume of water.  To determine how which wastes the most water, we need to know a few things.  For a bath, we simply need to know how much volume of water is used.  To determine the amount of water volume is used in a shower, we need to know the amount of flow coming out of the shower head, and how much time is being spent in the shower.
The amount of the flow of water in a shower depends a lot on the design of the shower head.  For this post, we will assume that the shower head will flow 2.5 gallons per minute.  A new shower head in the US will have a flow restrictor that limits flow to 2.5 GPM.

When I think of a standard bath tub, I think of a 30"x60" bath tub unit.  These units have a total volume capacity of around 40 gallons.  So, for this example, we will assume that a bath tub will be filled half way full for use.  That leaves us with a total volume of 20 gallons.

So now that we know the flow rate of the shower and the amount of volume used in a bath, we can do some math to compare.  A bath will use 20 gallons of water and a shower will use 2.5 gallons per minute.  How many minutes in the shower will it take to use more than the 20 gallons of water used in a bath?
Simply divide 20 by 2.5 to find out how many minutes it will take. 

Calculated out, this gives us 8 minutes.  So, if you take a shower for more than 8 minutes, you are using more water than if you took a bath in 20 gallons of water.

Now you've learned a new way of using math to conserve water.  And you're clean too.

For more on flow and volume calculators, try the online calculators at CalcuNATION.

Flow Measurement Calculators

Gallons Per Minute Conversion Calculator

Volume Conversion Calculators

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