eli5 Is there a reason the waste water like from showers can’t be filtered through pipes and used for toilet water?
In: 797
There is actually a section on this in the International Plumbing Code. I’ve not done a system like this, but it involves storage tanks. Self flushing timers for the storage tank, screens, and even a different color of water line for the water. Instituting a system would be incredibly expensive, and like most things, won’t be done en masse until there is a good financial reason to do so. Right now clean water is just too cheep for large scale adoption
The main issue is making an effective and affordable system that works for all homes, since building codes need to be followed. It is absolutely possible to do what you mentioned, but it depends on what soap you use, how dirty you were when you showered, how much money and time you’re willing to put into the filtration process, etc. This many variables makes it nearly impossible to make a system that can be certified as safe, inspected, etc.
If you had a brain and no building codes, you could do it pretty easily, but building codes need to account for people who aren’t smart or capable.
Water systems should definitely be re-designed for better efficiency. Why can’t shower water be reused for watering your plants? That would be a huge reduction in water use.
It can be. However, with showers you would have to store it. Instead, you can put a sink above the cistern, wash your hands then have it autoflush with the used water.
And surprisingly, these exist
My tight french neighbour has rerouted his shower waste into a barrel outside his house, at the top of the barrel there is an overflow which diverts back into the normal wasted when the barrel is full. Before he uses the toilet he goes outside to get a bucket of water so that he can just tip the bucket down to flush. I’ve worked out that all this effort saves him about 20 euros a year …
Yes because it would require adding a whole separate system of drain pipes to every home all the way to mains that feed into a plant meant to handle just that water. It’s cost prohibitive.
Among the other things people have said, wastewater systems works with gravity, so if you want to have such systems, you’ll have to pump water from your shower into a specific tank that will then emptied in the toilet’s tank, which adds to the complexity of the building and takes up a lot of space and energy for minimal gain in most cases.
Water is generally inexpensive. That is why it is so often our “go to” thing to use for washing away waste products.
Water treatment is generally expensive.
If you are in a place where it is difficult to get water (Like in space at the the ISS) is may be cost effective to treat water for some level of recycling. **Generally it is not cost effective to recycle water.**
In my rural area it is so cheap to pump potable water out of the ground with minimal treatment before using it for any use including drinking.
We flush all water into our septic system where it goes back to the earth.
But the well and the septic system are required for living here, so using them once you have them has very little extra cost.
Adding an additional filtration / purification system would be a huge expense.
a lot of places will do things like have your sink water be used to fill the cistern of your toilet before clean water gets put in to top it off for the next flush.
so you’d use the loo, flush, wash your hands and that water then goes to the cistern to wait for the next person.
no reason you can do this with things like a shower or bath too. I wouldnt do it with kitchen sink water.
I’ve seen it done but it was just the sinks and shower water captured and used for irrigation of certain plant beds. You could plumb it into the toilet if you wanted but adds complexity to the plumbing. My house is self contained but we have plenty of rain and store 70,000 litres of rain water captured from the roof and we process our sewerage through a textile media septic system which then irrigates a planted area, it can handle up to 1200 litres of sewerage per day, but we would never make that much. About every 7 years the system needs desludging by a truck that pumps it out. Environmentally it’s great but obviously wouldn’t be practical for lots of houses in a city area.
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