eli5 Is there a reason the waste water like from showers can’t be filtered through pipes and used for toilet water?
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Umm so many answers but as the son of a plumber all i can think of is how u gonna get that shower water back UP and into the toilent tank. You need a pump. Just think how much pubes and crap are gonna jam up that pump and how oftem youre gonna need to change it. NO THANKS!
No there are toilets that have the sink above it and that water is used in the toilet. Stuff is just not set up that way, and you also need to consider often times you are adding complexity if you wanted to do say a shower. You probably want to move that water into a tank to be accessed later, but now you have to sources of water and need a system that supports two sources, take from grey water, if empty use regular water.
In my country, fresh water is abundant. We have so much rain all year round that we never have droughts. (This may change with climate change, but I digress.)
So, the reason why we do not employ high efficiency water systems such as the one you describe is that the potential gain in water efficiency is not worth the potential health risks, or risk of damage to other, less robust systems. Additionally, the cost of manufacturing and distributing disposable filters which need to be changed regularly is more expensive than the water it would save.
Clean water is predictable in quality and should present no health risk.
In japan they have sinks on the top of the toilet tanks that drain into the tank so when you flush it reuses that water.
The reason is cost. Think about it. How would you get this shower water into the toilet tank? And how are you filtering it?? Water is most places is very very cheap
To use gray water, you have to install a complete system of tubes, pump and filters. And maintaining it .. then you have to make sure gray water system and drink water system can never connect…..
So basically it’s to expensive
In some countries it is used. For instance, you can buy toilets with sinks on top of the cistern. Fresh water used to wash your hands becomes “grey water” which is used in the cistern to flush the loo next time.
An interesting question! Water is, as far as I know, classified into three types. Clear water is that which is unsullied. Think of Spring Water, Well Water, Bottled Water, etc. Grey Water is any water that has been used before but does not have any toxic chemicals or excrement. Black Water is everything else. The regulatory bodies of our country have deemed that Black Water can never come back to a human again as we have no 100% guaranteed filtration systems. Also it’s gross.
Grey Water, on the other hand, can be and is reused. For example, after special filtration to get out soap and dirt and such, Grey Water can be used to water a lawn or to fill ballast to name just two. I once worked on a contained habitat project where the Grey Water was to be recycled for the plants they were growing for food.
I work for a water company. This is absolutely possible.
Typically. Water is piped from the reservoir to your home. You then use it and it becomes sewage. The sewerage leaves your house in a different pipe and is sent to a Water Treatment Plant. There it is usually treated until it is acceptable to release into the river/ocean.
The sewage can be treated to a much higher standard. Then sent back out in a third pipe as ‘Recycled Water’. This can be used for flushing toilets, some agricultural uses, and so on.
So why isn’t this common? short answer, it’s expensive.
Long answer; treating the water till it’s safe enough to use again is expensive. Usually way more expensive than using rain or bore water. Building the third network of pipes to distribute the recycled water is even more expensive. It really isn’t worth it unless you live in a part of the world with very limited water resources.
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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