Something I never see mentioned in these articles/discussions is the design problems. I’m a civil engineer who works in infrastructure maintenance, including sanitary sewers up sizing/repairing. The minimum design guidine for slope is 0.5% for sanitary sewers, but there are many old neighborhoods where the slope is as low as 0.3%.
The way those pipes continue to operate is the large volume of water that is sent through those sewers regularly, flushing away the solid waste.
If, theoretically, every house swapped tomorrow to a grey water system, we’d seriously struggle with blocked sewers and backflows regularly.
Until someone solves that part of the issue, this system isn’t practical for widespread adoption.
Given this, i think a potential current solution is mass gray water systems added to waste water plants. Many waste water plants have effluent that is safe enough to release to public waters or lands after treatment. This treated water could be used on a city wide grey water system used for garden and lawn irrigation. I think some places with scare water already have similar systems.
Most of these exisiting systems are meant more to service commercial/industrial/agricultural customers, it is unfeaseable to deliver grey water to every home or business. It would be incredibly dangerous to have the wastewater system directly hooked up to a potable water system. A variety of issues could disrupt the flow/treatment/monitoring of wastewater which could contaminate the drinking water system and its reservoirs/water towers and pose a serious threat to public health.
Most of these exisiting systems are meant more to service commercial/industrial/agricultural customers, it is unfeaseable to deliver grey water to every home or business
I’m not sure what you mean here. Even if you limit the great water system to large scale operations that would use the grey water, you’re still looking at billions of dollars to run the pipes plus all the pumps, sampling points, water valves, new water towers/resevoirs etc.
It would be incredibly dangerous to have the wastewater system directly hooked up to a potable water system. A variety of issues could disrupt the flow/treatment/monitoring of wastewater which could contaminate the drinking water system and its reservoirs/water towers and pose a serious threat to public health.
So can any surface treatment system that is currently used. Any city that uses rivers or lakes as their treatment centre already need to purify to a high standard and closely monitor quality of in and outflows. Additionally, most of those areas have their treated sewage outflow to the same body of water as they draw from. The whole point of designing a system is to build in backups and fail-safes to ensure those issues are identified and accounted for. It’s significantly cheaper than creating a whole secondary great water utility system, not to mention the additional costs for all those businesses that need to add another internal plumbing system
I suspect there is more grey water created in most homes than flushwater needed, and I’m not sure if even watering the lawn would use all the greywater a house might produce. Without doing the math, I suspect there would still be some amount of greywater moving to keep the pipes rinsed.
Something I never see mentioned in these articles/discussions is the design problems. I’m a civil engineer who works in infrastructure maintenance, including sanitary sewers up sizing/repairing. The minimum design guidine for slope is 0.5% for sanitary sewers, but there are many old neighborhoods where the slope is as low as 0.3%.
The way those pipes continue to operate is the large volume of water that is sent through those sewers regularly, flushing away the solid waste.
If, theoretically, every house swapped tomorrow to a grey water system, we’d seriously struggle with blocked sewers and backflows regularly.
Until someone solves that part of the issue, this system isn’t practical for widespread adoption.
Given this, i think a potential current solution is mass gray water systems added to waste water plants. Many waste water plants have effluent that is safe enough to release to public waters or lands after treatment. This treated water could be used on a city wide grey water system used for garden and lawn irrigation. I think some places with scare water already have similar systems.
Realistically, it’s better and more cost effective to add additional treatment to that water, and bring it up to potable standards.
Hundreds of kilometers of extra water main pipes, plus pumping stations and home services would cost trillions of dollars.
Most of these exisiting systems are meant more to service commercial/industrial/agricultural customers, it is unfeaseable to deliver grey water to every home or business. It would be incredibly dangerous to have the wastewater system directly hooked up to a potable water system. A variety of issues could disrupt the flow/treatment/monitoring of wastewater which could contaminate the drinking water system and its reservoirs/water towers and pose a serious threat to public health.
I’m not sure what you mean here. Even if you limit the great water system to large scale operations that would use the grey water, you’re still looking at billions of dollars to run the pipes plus all the pumps, sampling points, water valves, new water towers/resevoirs etc.
So can any surface treatment system that is currently used. Any city that uses rivers or lakes as their treatment centre already need to purify to a high standard and closely monitor quality of in and outflows. Additionally, most of those areas have their treated sewage outflow to the same body of water as they draw from. The whole point of designing a system is to build in backups and fail-safes to ensure those issues are identified and accounted for. It’s significantly cheaper than creating a whole secondary great water utility system, not to mention the additional costs for all those businesses that need to add another internal plumbing system
Depends on the usage in a given home.
I suspect there is more grey water created in most homes than flushwater needed, and I’m not sure if even watering the lawn would use all the greywater a house might produce. Without doing the math, I suspect there would still be some amount of greywater moving to keep the pipes rinsed.