Though I have a distaste for the waste of water, which mostly comes from my time living in Lesotho, I’ve been wondering how much money I save when I’m careful with water use — here, at home, in Southern California. When I turn the kitchen faucet on and off rather than let it run while washing dishes, or better yet, when I collect dishwater in a five-gallon bucket under the sink and use it to irrigate the lime tree rather than just run the hose on the lime tree for a five-gallon minute, how much money stays in my pocket — how much does my water bill go down?

First, the simple numbers on how much we pay for water piped to us from the Ramona Municipal Water District: The lowest tier is currently $5.65 for one hundred cubic feet (HCF), which is equivalent to 748 gallons. (This price includes a “water charge” of $4.67 plus an “electric charge” of $0.98 per HCF.) That works out to approximately $0.008 per gallon; in other words, a little less than a penny per gallon. Or, that five gallons on the lime tree is worth four cents.

We’re thoughtful about our water use in this yard, and over the past year and a half of living here we’ve improved our efficiency such that our last water bill was our lowest ever — even though we’ve added a third person to the household and many plants to the yard. Congratulations to us? What was our reward? How much did we save?

The bill period was November 20, 2014 to January 20, 2015 — two months — and during that time we used a total of 3 HCF, or 2,244 gallons. We paid $74.26 for this.

Compare this bill to the same two-month period the year before. From November 20, 2013 to January 20, 2014, we used 7 HCF, or 5,236 gallons. For that we paid $93.57.

So we used 57% less water than last year while our bill went down 20%. Only 20%? Why?

The fixed fee of $57.22 added to each water bill, called a “system charge.” Charges for our actual water use are added on top of this fixed fee. Regardless of whether we ever flush a toilet or turn on the irrigation system, we pay $57.22. I think of it as the fee for retaining the capability of flushing the toilet or turning on the irrigation system.

This fixed system charge was the largest portion of both of the above bills. For our most recent bill — our lowest ever — we paid the system charge of $57.22 plus $17.04 for our actual water use. For the bill of the same period the previous year we paid the system charge of $57.22 plus $36.35 for actual water use. Therefore, our actual water use accounted for 23% and 39% of these water bills, respectively.

Put another way, we had no control over 77% and 61% of these water bills — which is why taking big steps to be careful about our water use resulted in only a small dent in our overall cost of water.

Put yet one more way, cutting our water use by more than half only cut our water bill by less than a quarter.

That’s discouraging. But it’s a separate issue.

Back to our original question: does it pay for us to conserve water? Simply, yes. We reduced our consumption and our bill went down. Specifically, as we figured out above, every gallon we conserved, or didn’t use, was $0.008 that stayed in our pocket.

Now, does it pay to haul those buckets of dishwater out to the lime tree? That is mostly a question of how much time and effort it takes. The five gallons of water in each bucket is worth four cents. Is the time and effort required in hauling the bucket out and applying it to the lime tree worth more or less than four cents?