Water for home patients

Saving/Re-using Reverse Osmosis RW at home.

Reverse osmosis RW can be reused, and re-use options should be offered to all/any home haemodialysis patients.

Some simple plumbing steps (see Figure 1) with a one-off cost of ~AUD$ 1,500-2,000 can save significant amounts of perfectly safe, effectively ‘potable’ waste water.

Figure 1: Recycling reverse osmosis RW at home

Figure 1: Recycling reverse osmosis RW at home

Some home water re-use options might include:

  • Pipe-and-tank systems for garden maintenance.
  • Store-then-drawn systems for:
    • Laundry use.
    • Toilet flushing.
    • Dishwasher use (ensure an added softener).
  • Animal/stock watering.
  • Goodwill, over-the-back-fence, sharing for neighbour use.

These reuse systems are cheap to install and are much appreciated by patients. They help defray the utility costs of home care. They allow patients to take ownership of the part they can play in ‘making dialysis green’.

As regards neighbor-sharing, while reassurance may be required to confirm the quality of shared water, once it is understood that RW is ‘pre-patient water’ and not ‘used dialysate’, uncertainty commonly disappears.

Remember, while outmoded regulation still prevents a recommendation that the RO RW is fit for human consumption, it does meet all EPA and WHO standards for potable (drinkable) water for human use.


RW re-cycling through the RO – ‘continuous looping’

Another re-use option is to re-cycle the RO RW back throughthe reverse osmosis system in a continuous loop. This has been reported previously (7).

This is a useful option to consider in facilities where access to a reliable municipal water supply is limited, there is a reliance on rain water, or the unit lies within an arid or drought affected area.

This system comprises:

  • A holding tank
  • A larger storage tank
  • A reversible pump
  • And… a conductivity probe at the RO.

It allows reverse osmosis RW to be ‘continuously looped’ and to be re-used in the dialysis process.

After mains water priming, a recycle switch directs reverse osmosis RW away from drain and into ‘recycle mode’

‘Recycle mode’ directs the RW to the holding tank and storage tank, then back to the RO system for re-use in the dialysis process.

A reversible pump drives the system. It is reversible to allow the storage tank to be back-filled (diluted) by mains water if a conductivity probe, located in the RO, detects a rising (i.e. unacceptable) conductivity reading in the recycling RW and triggers an alarm.

Once the storage tank is satisfactorily diluted, recycling can recommence.

Figure 2: Diagram of recycled RW system for use in haemodialysis

Figure 2: Diagram of recycled RW system for use in haemodialysis

While the additional set-up costs are contentious, similar systems have proven to be relatively inexpensive. Local cost/benefit analyses will be performed.

Be aware that water quality needs to be assured, and disinfection processes will need to be maintained to ensure that the water delivered from the tanks remains within guidelines for water used for the dialysis process.

A note regarding septic tanks

When thinking about the disposal of dialysis effluent, there is one very important consideration – both for haemodialysis and peritoneal dialysis patients.

Dialysis effluent should not be be drained into a septic tank for two reasons:

  1. The volume of water that haemodialysis uses will quickly fill a septic tank requiring more frequent pumping and drainage.
  2. The saline (HD and PD) and/or dextrose (PD) concentrations in the effluent dialysate can change the microbiological pH of the septic and can cause blockage and overflow. The high glucose content of PD effluent can also promote the formation of a co-polymer … a little like thick egg white … that coats the surface of the septic and can block the lateral distributors.

It is therefore not recommended to drain dialysis effluent to a septic system if the household relies on a septic tank to break down household and toilet wastes.

Alternative methods for dialysis effluent disposal – such as rock pits and/or leach-fields – should be considered.

Read Professor Agar’s personal viewpoint on Septic Tank in the home.