Why is conserving household water usage important? Doesn’t all the water end up at a treatment plant and go back into the supply at some point? Is water actually being depleted with things like long showers? Where does it go?
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>Why is conserving household water usage important?
Because preparing water for that purpose is expensive. Well, actually kind of cheap, when you think about how great running water is, but water-treatment plants and distribution networks have limited capacity that it costs money to build, expand, and maintain.
>Doesn’t all the water end up at a treatment plant and go back into the supply at some point?
Not exactly. Sewage from household use gets treated, *enough to be released back into [the river or whatever],* but that’s not the same as *enough to be recycled into people’s drinking water*.
For stuff that drains into a sewer, it really isn’t. That type of direct usage is like 4% of water use. Watering a lawn can add up to something significant, but otherwise humans use most of their fresh water for agriculture or industrial stuff.
Not always. If the supply is an underground aquifer, for example, then sewage water doesn’t go back there. It goes into some river usually, from where it can evaporate or get to the ocean, so it can’t always be reused.
The world only “creates” so much fresh water each year through evaporation from the ocean and rain over land. That fresh water is stored in aquifers and reservoirs, the main sources of our fresh water. If we use water faster than those aquifers are replenished, bad things happen: wells dry up; rivers, lakes, and streams dry up; land subsides; sinkholes; saltwater intrusion into aquifers; hydroelectric dams stop working, etc.
Reducing water use, reducing impervious surfaces (e.g., pavement) so that rain can infiltrate instead of running into a storm sewer and straight back into the ocean, and of course curbing climate change are the main ways we can influence how quickly the aquifers and reservoirs are replenished.
The supply of water is effectively infinite for human purposes. The supply of potable water, however, is sharply limited by our capacity to purify water effectively. If you leave your tap running, that is water that someone could have been drinking that instead just goes back into the system.
Most places don’t recycle water. Fresh water comes down in the rain, and it gets into rivers, and then the water is taken from the rivers, purified a bit and you drink that. When you pee and poop, the sewerage is treated a bit to make it less nasty, then discharged somewhere that isn’t where you drink – into the ocean or downstream on the river – hopefully not upstream of another town. (Actually, because of this problem it’s more common to get water from aquifers, where the river water percolates through the ground for a while which filters it)
The dirty water ends up in the ocean where the sun evaporates it, and only the water evaporates and rains and so that’s how it gets fully purified.
We can’t really control where the rain goes – your town gets a set amount of it, and that’s that – if you use more water than it rains, you run out. You’re conserving rain.
1. Saving money. Water isn’t super expensive, but a house also uses a lot of it.
2. Most of the water ends up in treatment plants, but the more water people use, the more treatment plants we need to build. Things like golf courses and lawns also don’t return water to the supply.
3. A small portion of water ends up in the ocean, becoming salt water. It’s much more expensive to remove the salt from water than getting fresh water.
4. It’s not easy to move fresh water back to the source. Most places rely on rain and snow to do this, then use gravity to get the water where it needs to be. Moving cleaned water from a downriver treatment plant back to a reservoir is very expensive.
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