This continuing drought, high temperatures, and stage 2 water rationing in Shawnee underscors the fact that we are all in this together. We have to work together to conserve our water and give our treatment plant some relief. Our decision to wash our cars should be made with our responsibility to conserve water in mind. Here are some facts that might help you.
Let’s talk about your cars. Should you wash them in your driveway or at the local carwash? As with all questions ecological, it depends...in this case, on your hose habits. The average hose of 5/8 inch running with 40 pounds of water pressure per square inch uses about 11 gallons of water per minute, so if you spend 10 minutes washing your car you use more water than you would in seven loads of dishes in the dishwasher. If you use a nozzle with the capacity to halt the flow of water, you’re in better shape, and even better if you use soap, a bucket and sponge and elbow grease. Power washers are a good tool for the home washer, too.
Automatic car washes come in three designs: in-bay stationary, in which the car doesn’t move (the thirstiest using 17-69 gallons of water per vehicle); conveyor, in which the car moves through a tunnel (similar to the in-bay stationary); and the coin-operated do it yourself bay. This last option is the most efficient, using an average of 12 gallons of water, since you are directing the spray of water. If you are super efficient at home on your driveway, you might be able to compete with design three.
But there is more to consider. When you wash your car on the driveway, the water drains into the storm gutter system, along with the chemicals you used to wash the car and those on the car before you washed it. It’s almost as bad if you wash it on your lawn, it is preferable to wash your car on grass or some porous material that keeps the dirty water out of the storm drains. That water goes somewhere! Under the Clean Water Act, carwashes have to follow certain guidelines when collecting and disposing of their dirty washwater, and most of it ends up in the municipal wastewater plants, to be cleaned and treated, so there is that advantage, unless you are careful at home not to let the water drain into the storm drains (not an easy task)
One more thing. Try to avoid using cleaning products that are toxic ammonium bifluoride and hydrofluoric acid-based cleaning solutions in favor of phosphate free biodegradable solutions. Cleaning solutions certified by EcoLogo are considered safer to enter the water supply, and there are some waterless cleaning agents labeled “low VOC” which you might consider.
So it is not just how much water your use, it is where it goes.