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Water that Tree - A Real Bargain!
See also Watering
your Tree
City of Ottawa Forestry Services has estimated the cost of watering
trees for people on city water. (Note that this does NOT apply to
those using well water.) During hot periods this summer, the city
will be issuing tree watering advisories. Help keep our city green
by taking care of the trees near you!
- A cubic metre of water costs $0.58 on your water bill, but double
this to include the sewer surcharge as well:
$1.16
- A cubic metre of water = 220 imperial gallons
- A trickle of water left on overnight (8 hours) will deliver
40 imperial gallons of water to your tree (40 gallons of water
in 8 hours converts to 22.7 litres an hour. So your hose should
be trickling at a rate that will fill a 2-litre soft drink bottle
in about 5 minutes.)
- At that rate it will take 5.5 nights to provide a cubic metre
of water to the tree
40/220 = 5.5 nights/m3
- From 1 May to 30 September, there are 153 days. If you water
your tree every night during that time, it will cost $32.27
153/5.5 x $1.16 = $32.27
In other words you can water your tree overnight, every night,
for the entire summer for just over $30.
And it just gets better and better
There are other points to consider:
- Both May and September are usually relatively wet months, so
the greatest requirement for water can be expected to be in June,
July, and August. So instead of 153 days, the more conservative
estimate of 92 days is more accurate.
92/5.5 x $1.16 = $19.37
- Watering every night would be too much. Generally, every second
night is sufficient, even under drought conditions. So divide
your cost by 2 reduces it to $9.69
- That's assuming NO RAINFALL. If it rains, the cost will be further
reduced.
- Multiple trees share root space so the cost of water per tree
is further reduced.
- A large diameter (100-cm) high-water-demand tree can take up
about 40 gallons of water from the soil on a typical windy summer
day. Many city trees are half that size so water demand will also
be lower.
City Forester, Parks and Forestry Services
Ottawa Forests and Greenspace Advisory Committee
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