Sunday, March 16, 2008

I Saved $9.00 on Water Last Year Using My Shower Bucket

Here are the current prices for water and sewer in Calgary, for residential metered customers. (Source: City of Calgary website).

Water
$10.87 service charge every 30 days
$1.1853 per cubic meter usage charge

Sanitary Sewer Service Charge
$9.64 service charge every 30 days
$0.6027 per cubic meter usage charge

Now, I can't do anything about the fixed service charge, short of disconnecting altogether, and that's just not an option I would even want to consider.

The usage charge is within my control. Or at least part of it is - what my family does is really up to them. I haven't turned into an eco-tyrant just yet. Trying to set an example instead.

Since early 2007 I have been catching water from my shower in a big bucket and using it to flush the toilet. The bucket holds 17 litres, and each toilet flush uses about 15 (not six as I originally estimated). I can safely say I have used this on 90% of the days in the past year for at least 15 litres of water per day.

Calculating the Savings in Water and in Money

In one cubic metre of water, there are 1,000 litres.
The usage cost for getting one litre of water is $1.1853 / 1000.
The usage cost for disposing of one litre of water is $0.6027 / 1000.

When I use shower water to flush the toilet, I save myself both the purchase price of the 15 litres and the disposal cost.
Savings per litre: 1/1000 of ($1.1853 + $0.6027)
Savings per bucket is 15 times the savings per litre.

In one year, at 90% usage, I save 15 litres a day for 90% of 365 days.

Putting all of this together, the amount of water I have saved from use (and therefore from processing by the City's system) is 4927.5 litres. I think I can safely round this up to an even 5,000 litres to make it easier to calculate.

5,000 litres is 5 cubic metres.

By not using that 5 cubic metres, I save $5.9265, or about $6.00 per year on the cost to buy the water, and $3.0135, or about $3.00 per year on the cost of disposing of it.

It's like I'm getting paid $9.00 a year and getting my exercise hoisting the bucket.

Not a huge saving, I agree, not for one household.

But imagine if just one percent of the people in Calgary did this. That's about 10,000 people. Instead of 5 cubic metres per year, it would be 50,000 cubic metres, equal to 50,000,000 litres (50 million). Maybe it sounds like a tiny amount compared to the approximately 450 million litres per day we Calgarians are accustomed to using, but it's a start.


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