Induced Demand


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I was on the phone the other day having a conversation about greywater with a person enrolled in an entrepreneurial program. She asked me an excellent question: did having a greywater system cause me to use more water?

She was alluding to a concept known as induced demand. In other words, when you have more of something you use more. Buy a hybrid car and you end up driving more miles since you don’t pay as much for gas. Build a four lane highway instead of a two lane one and so many more people end up driving that you end up with worse gridlock.

I’d never thought of induced demand when it comes to greywater, but it’s a good point. Did I plant more fruit trees because I had a greywater system? Has this caused more water consumption in our current drought? Honestly, I think the answer is yes.

You could probably find induced demand between the lines of David Homgren’s permaculture principles. But perhaps we should insert a thirteenth principle: acknowledge induced demand and work to prevent it. Simply being aware of the phenomenon is a good first step in avoiding its pitfalls.

My original greywater system consisted of a tank and a hose to drag around to a bunch of trees. I’ve since simplified the system. It’s now just a pipe leading from the laundry machine to one tree that needs just about as much water as we do in laundry each week. My second system is more of a 1:1 match between the waste water and the demands of the landscape.

Have you encountered induced demand on your homesteading path? If so where and how?

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  1. Pingback: Induced Demand | NewsSum

  2. This is the problem I am struggling with as I size and design the solar PV system for my home. It would not cost much more at the time of installation to “upsize” the system about 10%, but would that just assuage my guilt and cause me to be less diligent about electricity usage? I think the answer is yes.

    Induced demand just makes me flash back to first quarter economics at the University of Minnesota. Ugh!

  3. Induced demand is definitely something to watch out for. I’ve been stopping up the tub when I shower and bailing that water out into my watering can for my balcony vegetable garden. Since that water is getting used to grow food I haven’t been as conscious of shortening my showers as I otherwise would be in a drought. I’ll need to change my thinking!

  4. Your water use may have gone up, but in the global picture, it’s a wash. That water would have been used elsewhere to grow the fruit you will harvest off the tree.

  5. It does not sound as if you are overwatering your trees. By using more it seems you are making good use of your resources instead of paying for water just for the trees. Do you trees know there is more water and they have started being gluttons?

    When I have an excess of a resource, sometimes I am not so conservative than I would be than if I had less of the resource and worried how to obtain more. When I have water dripping from the window ac, I do give certain plants more water, but they might suffer if I did not use the excess. They perk up, so I assume I have not watered in vain.

    If I have a gallon of ice cream, I eat more than if I only have a pint on hand. So, I suppose that is my version of induced demand.

    Oh, I have a real homesteading example: Now that I have hens that lay eggs, I do eat more eggs. But, that is not a bad thing. Eggs are good for health, especially if the hens feed on grass so eggs are full of Omega3, are happy, and amuse me. I don’t have to purchase eggs with more Omega6 and purchase Omega3 supplements.

  6. Well, it was cheaper to get an 8 chicken subscription from a local farm here in Oregon, but we rarely eat whole chickens! I roasted maybe one last year, and this year I will be roasting 8 of them?? 😛 but then again, otherwise we would get occasional drums or thighs, and we haven’t done that in awhile asides for making cat food from.

    • Once you get whole chickens, you could cut them up and store the pieces in portions you would use. Or, you could roast the chicken and freeze it in portions you would use. I have been cutting up whole chickens for over 45 years, and it is not so hard, especially with a very sharp knife. So, getting cheap whole chickens seems like a deal, especially when there is some loss that could go to the cats.

    • Even though it works out cheaper than getting already cut chicken parts, it always seems like kind of a waste to me to cut up a whole chicken even though we would eat every bit of it, down to making stock from the bones. I guess when I say cheaper, I mean the 8 got lowered to 4.45 a lb instead of 4.95 I think. They are pastured poultry, and picked up the day of slaughter. The cat isn’t getting any of it lol. I think what we’ll do is just keep them frozen until we’re in the mood for a roast chicken.. I might part one for maybe a soup, fried chicken, and shredded chicken with handpulled korean style noodles week. 🙂

  7. Maybe I’m missing something, but when it comes to gray water from your washing machine, you would have used that water (for laundry) regardless. Reusing it to water your trees has no net increase on your water usage, so it still seems like a savings overall. Of course, if you are taking longer showers or doing laundry more frequently because you feel like, meh, I’m reusing the water, then it would be different. But otherwise, you’re basically directing your wastewater into the garden and into the water table instead of the sewer, and if that allows you to grow more fruit – awesome! Of course it might cause some induced demand, bc you can grow more without wasting water and without paying more, but I just don’t see it as a problem.

  8. I bicycle more because I own a Prius (and I drive less than when I owned a conventional compact, because my overall awareness about carbon footprint has been raised. However, I often offer to drive if the other person in the carpool has a gas guzzling vehicle. This is NOT an example of induced consumption – its an example of least worst consumption.

    Since we installed a laundry-to-landscape system, I have used more water on the fruit trees and veggies that are not watered by the L-To-L system, because its become glaringly obvious how water deprived my plants have been until now. I just want all the plants to be as happy as the ones on the laundry-watered row. This IS an example of induced-consumption. I compensate by letting the native plants in front limp along on the moisture that falls on them at night and early morning.

  9. Prius ownership *definitely* upped my milage, no two ways about it. I think that is a example of induced demand with a negative effect.

    I installed solar panels last fall and put in a heat pump, so I have AC for the first time in 15 years. Am I much more liberal about turning the heat or AC on now that I have solar panels and a more affordable energy source? You bet. But, I don’t see that as a bad thing. I have made my life dramatically more pleasant two months of the year, which is an energy expenditure that I didn’t have, but I have attained it from a clean source. I think this a positive form of induced demand.

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