Thoughts on Home Water Capture and Reclamation
Whiskey is for drinking. Water is for fighting over.
- Samuel Clemmens (Mark Twain) - potentially apocryphal
Reading the news lately about water shortages in American Southwest and South and Central America1,2 and predictions about periodic flood conditions in other places, I have been thinking about home water capture and reuse. That is, how can I store the water coming on to my property and use it later and how can I be more efficient about the water we use.
Water reuse in the home is going to be problematic because the pipes in the house really only flow one direction. Water comes into the house from the water main clean and, regardless of how it’s used, flows out to the sewage line as dirty.
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Really, though, I don’t need clean and treated water going into the toilets. Water used in bathing and cooking could be filtered and sent into the toilets instead. Putting in the pipes, particulate filtering, and oher necessary components to achieve that would require significant work. This seems like something that could be done when first building a house but is likely impractical for an existing structure.
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Water capture is, in some ways, easier. Most simply, water can be captured from roof downspouts in rain barrels and used for low pressure garden irrigation. In theory, a cistern could also be dug into the ground to capture runoff and, using a pump mechanism, water could be pulled from the cistern for similar purposes.
Neither of those approaches, though, provide water for use in the home. To accomplish that goal, there are at least two challenges which need to be solved. First, neither rain water nor groundwater are considered safe for bathing or drinking without processing. Notably, PFAS chemicals have been found in rainwater in multiple places around the world. Rainfall and groundwater would also contain particulates that would need to be filtered out to prevent clogging of pipes.
Secondly, to inject into the home, the water capture system would need to be pressurized (most city water mains supply water at between 45 and 75 psi). And obviously this would also require plumbing work to provide an input from the water capture system to the house. It would only require plumbing connection at the input to the house though, so should be significantly simpler to add to an existing structure than to create the secondary system of pipes within the house required for reuse of water in the home.
