The purchase of a good-size rain barrel to which a hose can be attached or a watering can filled can eliminate outdoor use of drinking/tap water. This will save you money and help reduce GHG emissions.
What you pay on your monthly water bill goes towards the cost of current water and wastewater treatment and toward the ongoing creation and maintenance of treatment facilities. The water you use everyday requires large amounts of electrical energy to treat, deliver and remove wastewater/sewage from your home.
An example of the associated cost savings and GHG emission reductions by collecting rain water for irrigation is provided below. Based on a house with a 102 m2 (1,100 ft2) roof surface (Home Energy Chronicle SESCI) from April to October inclusive, the average rainwater collected is 35.8 m3.
Greenhouse Gas Savings April to October – 7 months
35.8 m3 x 1.7534 kg/m3 (water and sewer factor) = 62.7717 kg of GHG emission reductions
Cost Savings April to October – 7 months
35.8 m3 of water x $3.298* (water and sewer charges) = $118.07
*In 2022, the water rate for residential homes (up to 60 m3) = $2.0487 per cubic metre plus sewer charges of $1.2493 per cubic metre for a total of $3.298 per cubic metre.
That is, one household within the City of Edmonton, having a 102 m2 (1,100 ft2) roof surface, can save $118.07 on their water bill during the 7 months quoted by using rain water to water their lawn and garden. They would also reduce their share of GHG emissions by 62.7717 kg per year.
Cost-Savings Based on Rain Barrel Size
1,000 litre (220 gallon) rain barrel holds 1 m3 of rainwater.
A 1,000 litre rain barrel filled only once would reduce GHG by 1.7534 kg/m3 = 1.7534 kg CO2.
Cost savings on the water bill per filling = $3.29.
570 litres (125 gallon) rain barrel holds 0.6 m3 of rainwater.
A 570 litre rain barrel filled only once would reduce GHG by 1.7534 kg/m3 x 0.57 = approximately 1 kg CO2.
Cost savings on the water bill per filling = $1.87.
205 litre (45 gallon) rain barrel holds 0.2 m3 of rainwater.
A 205 litre rain barrel filled only once would reduce GHG by 0.359 kg CO2.
Cost savings on the water bill per filling = $0.67.