Green dialysis: what to do with discarded water used during dialysis?

Global warming is a growing threat to our health. Dialysis, while sustaining the lives of millions worldwide, has a significant environmental impact. Think of your last dialysis order. Perhaps the Kd was 500 ml/min for four hours. That’s 120 L. Dialysis units may waste up to 2/3 of the reverse osmosis (RO) water used for making dialysis. So add another 240 L. If you include additional saline used for used for priming and cleaning HD machines we may use between 400-500 L of water per 4-hour treatment. And that’s with a modest Kd of 500 ml/min.

Considering the global dialysis population, over 150 billion L of water are likely used every year with potentially 2/3 of that water discarded prior to dialysis. That’s about 40,000 Olympic swimming pools filled with wasted water. It should be noted that depending on your unit’s specific water system there may be less waste and increased recycling opportunities, but overall this remains a significant area of impact for dialysis on the world. And these concerns do not include the power and plastic needs generated by dialysis, which are also significant.

Does it have to be this way? RO “reject” water is more than just potable. It went through particulate filters, carbon filters, and water softeners prior to reverse osmosis. What emerges is practically expensive mineral water. It passes the WHO/EPA requirements for drinking water though is not legally considered potable.

Instead of going down the drain, RO reject water could be used for:

• Steam generation for hospital sterilization 
• Laundry services 
• Sanitation services 
• Landscaping 
• Almost anything you already use water for 

Reusing dialysate is more challenging given the higher conductivity (salinity) and the requirement for either recurrent RO or sorbent therapy. This can be cost-prohibitive and technologically challenging.

How much RO water does your unit’s system reject?  
Is there a way to use that water if it is not already being used? 
Beyond that, can recycling be further emphasized for both in-center and home patients? 
Perhaps in some places solar-assisted hemodialysis is an option?

One day perhaps rejected RO water can grow fruit and veg on the roofs of dialysis units. Providing sustainable, affordable nutrition to those who need it most.

If you are intrigued, the following resources offer a starting point to making dialysis more environmentally sustainable.

• UK Center for Sustainable Healthcare – Green Nephrology Network.
• Green Dialysis – An Australian based resource website.
• Green dialysis: the environmental challenges ahead.
• Reusing and recycling dialysis reverse osmosis system reject water.
• Toward greener dialysis: a case study to illustrate and encourage the salvage of reject water

Robert Rope, Nephrology Fellow- Stanford