Not that long ago we paid a total of $2.64 per 100 cubic feet of water used, now it is up to $3.9162 per 100 cubic feet. That is a 50% increase in just over two years. Our summer period water and utility bill from the City of Victoria came to almost $500!
I decided to look into getting a rain barrel to see if I could reduce our summer time use of water. The prices I found for 300 to 400 litre barrels was about $100 to $200. Being an analytical guy I thought I would do some math and see if it would make any difference financially for us.
Working with a 400 litre barrel, this is 14.125 cubic feet, or in water rate terms $0.55 worth of water. For me to save enough water to pay for the cost of the barrel, I would have to fill it up and use it 180 to 360 times to cover the cost.
So how many times would I expect to be able to fill this barrel in the period from May 1st to September 15th, roughly the limits of when I need to water around here? The barrel would be getting water from about 400 square feet of roof and using the data from the UVic weather network for my neighbourhood, I could come up with an approximate number times I could fill it. Looks like about 8 times is what would be a 'normal' year, if I am lucky that could be as high as 12 times, but I am going use an average of 8 times a year. It would take 23 to 46 years for me to save enough water to pay for the initial cost of the barrel.
So how expensive would my water rates have to be to make the rain barrel a useful investment? If I am willing to allow for a seven year return on the investment, and this is longer term than 90% of people consider worthwhile when considering home efficiency improvements, I am looking at water rates of $12.50 to $25 per 100 cubic feet of water, three to six times as much as I pay now.
The normal pay back time that makes the majority of people choose to do something is under three years. At three years the water rates would have to be $30 to $60.
3 comments:
I've considered buying a rain barrel myself, so your analysis was informative.
Once, when looking into commercial composters, I was shocked at how expensive they were. I mean they are only plastic, not much different from a plastic garbage can. So I bought a plastic garbage can! Cut the bottom out, drilled a few holes in the top for air and voila -- one functioning composter.
Rain barrels are no different. Type in 'diy rain barrel' into Google and you'll find links to sites with instructions where you can built them for a fraction of the cost of a store-bought system.
HTH,
Mike Laplante
Don't forget to take into account the other environmental benefits of rainwater harvesting - increased infiltration, groundwater recharge, reduced downstream erosion in streams and creeks, increased capacity in the stormwater system, less inflow and infiltration into the sewer system (which in Victoria, could mean millions of dollars saved for the sewage treatment project)
Mike, I will take a look for online DIY options.
Meanwhile on the point that there are other benefits, most of the ones listed would not seem to apply in my situation. Any rainwater I do not use sinks into the ground and not into the sewer system. All I reduce is my use of water from the reservoir, and then not by much at all.
I am assuming the high water rates we pay covers all the environmental costs of the system. I might be wrong with that as we have a publicly owned water system and these are typically much less efficient than privately operated ones.
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